Costruire un computer/Componenti

Prima di immergersi nel web ed iniziare a spendere un sacco di soldi in componenti costosi, ci sono due importanti domande a cui bisogna porsi:

1. A cosa useremo il computer?
2. Ci sono dei componenti del vecchio computer che sono usabili--oppure si vogliono riusare pezzi del vecchio computer?

(Spesso, si vuole cedere il proprio vecchio computer a qualcun'altro, in questo caso deve rimanere funzionante, oppure esso potrebbe essere talmente vecchio che non si vuole usare nessun vecchio componente, perché rallenterebbe troppo la nuova macchina.)

Scegliere i componenti

Quale sistema operativo si userà?

Prima di comprare i componenti, bisogna essere sicuri che essi siano supportati dal sistema operativo che si è progettato di usare. Attualmente quasi tutti i prodotti sono disponibili con i driver per le versioni correnti di Windows (generalmente 2000, XP o superiori); se si vuole usare un sistema operativo alternativo, si devono fare alcune ricerche -- esistono molte 'Liste di Harware Compatibile.

Liste di hardware supportato da Windows

Molti processori e schede madri basate sull'architettura i386 o x86_64 sono supportati da Windows XP. In modo più semplice, questo significa che tutti i processori disponibili sul mercato (specialmente AMD o Intel) sono compatibili.

Per altro hardware

Microsoft Compatible

Lista di harware supportato da BSD e simili

• DesktopBSD, vedi FreeBSD 5.4/i386 e FreeBSD 5.4/amd64
• Dragonfly BSD
• FreeBSD
• NetBSD
• OpenBSD
• PC-BSD, vedi FreeBSD 6.0/i386

A too small power number doesn't run your high power devices (like optical, CPU and Graphics Cards). For certain graphics cards (especially high end ones with inbuilt fans), a recommendation of 350W is required. In general, if your motherboard has a 24 pin power connector, choose one which is at least 300W as the 4 extra pins are for high power applications. When in doubt, buy a more powerful PSU.

• Case Fan: Some cases have case fans. Make sure to choose one which matches your CPU interface on the motherboard. The best option is to purchase a 4-pin Molex connector fan as some motherboards do not have three pin fan ports. Although most motherboards fit most cases, it is the position of the case fan that affects speed and stability of the system. A good case has the fan aimed directly at the CPU for best results.

If you plan on building a high end gaming PC, you might want a case that looks good, and a much more potent power supply. For the more aesthetically inclined, there are countless companies who make designer cases that will suit many personal preferences. A power supply with more than 400 watts is usually more than is required by most people, and will allow you to power high-end graphics cards, cooling systems, and aesthetic enhancements such as cold cathode lights, cooling equipment, and other such things.

In all cases you should try to check reviews from a computer hardware site before you decide to purchase a power supply; quality can vary greatly and wattage output is frequently overstated. Quality power is also usually more efficient, so it will produce less heat and its fans can run at lower, quieter speeds. Manufacturers sometimes try to make passive, or fanless, power supplies, but in most cases they will end up running dangerously hot, and so are only suitable if you plan to add your own cooling solution.

CPU (Processor)

The Central Processing Unit (CPU) is the heart of your computer as it performs nearlly all functions that require extensive processing power. Therefore, it is very important that you choose a suitable CPU for your function as the choice of CPU directly affects the speed and stability of your system.

Before we can explain differences between CPUs, you must first be familiar with certain CPU properties.

• Clock Speed, measured in Gigahertz (GHz), or Megahertz (MHz) on older systems is the number of calculation cycles that your CPU can perform per second. Therefore, a higher clock speed generally points toward a faster system. But not all CPUs perform an equal quantity of work per cycle, meaning two CPUs at the same clock speed can potentially perform at very different levels.
• IPC, or Instructions Per Cycle is the amount of work a CPU can do in a cycle. This varies with diffrent properties of the CPU.
• Front Side Bus Speed (FSB) is the rate at which the CPU communicates with the motherboard Front Side Bus components in MHz. A larger FSB value shows that your CPU is able to communicate with other components on the motherboard (and thus your system) faster.
• Interface: CPUs must connect to motherboards via a series of connectors. It is VERY important that your CPU interface is a COMPLETE MATCH to your motherboard CPU socket otherwise you would be wasting money on a piece of spare silicon.
• Bit-Rate: Most modern CPUs are of the 32-bit system which work fine with most modern operating system and hardware. Higher end models are the 64-bit system which may allow faster CPU processing capabilities due to the larger band-width, but not all operating systems are compatible with the newer 64-bit format -- they will still run, but without a major performance boost.
• Hyper Threading (HT): Hyper-threading is a new technology of parallel processing which instead of one single core, your CPU is able to have separate cores working on different tasks which greatly speeds up the system speed. However, Hyper Threading technology requires a motherboard that supports Hyperthreading technology which are generally very expensive. And of course the software you use has to be optimized for Hyperthreading to give more speed.
• Manufacture and Model: There are two main manufactures of CPUs Intel and AMD, each having advantages and disadvantages that would be explained below.
• L2-Cache: the amount of Memory dedicated for the CPU in MB, generally, the larger the L2 cache, the faster your system would run. However, L2 cache uses a lot of transistors, and the larger the cache, the transistors needed, which consums more electricity, and outputs more heat.
• The Core of the CPU is the heart of the CPU. Often several cores will be marketed under the same name, so look at what core you are buying.

Now, one of the most common mistakes of choosing a CPU is by ignoring the fine print of CPU specifications while relying completely on the clock speed. CPUs specs are written in full, I give a brief explanation of the spec, eg.

Intel Pentium 4 3.2GHz LGA775 FSB800 HT L2-2MB

Model: Intel Pentium 4
Clock Speed: 3.2GHz (=3200MHz)
Interface: Land Grid Array 775
L2-Cache: 2MB (=2048 kB)
Other Spec: HT technology

The consumer logic for processor speed may be misleading because many consumers think that clock speed, which is measured in gigahertz (GHz) or megahertz (MHz) is equal to system speed. While the higher the clock speed the CPU is able to do cycles more frequently and it does have a fundamental effect on speed, it is not the sole factor as the number of calculations per cycle is different for each different manufacturer and model.

Intel classifies its CPUs using a series of numbers. 3xx, 4xx, 5xx, 6xx and 7xx of which 7xx being the highest end products. Generally, the higher the number, the faster the CPU and the more expensive. usually, models and ratings correspond.

• 3xx Series: Intel Celeron (L2-128KB)
• 4xx Series: Intel Celeron D (L2-512KB)
• 5xx Series: Intel Pentium 4 / Celeron D (L2-1MB)
• 6xx Series: Intel Pentium 4 / Pentium 4 XE (L2-2MB)
• 7xx Series: Intel Pentium 4 XE
• 8xx Series: Intel Pentium D
• 9xx Series: Intel Pentium D

the number followed by suffix J signifies XD technology

eg.

Intel Pentium 4 3.0GHz L2-1MB with HT --> Intel Pentium 4 530J

AMD CPUs are even more confusing in classification. The AMD Athlon CPU rating are NOT of the actual clock speed but rather the equivalence bench mark performance corresponding to a comparison to the AMD Athlon Thunderbird 1.0Ghz. The conversion Table is as follows,

AMD Athlon 1500+ = Actually runs at 1.33 GHz 
AMD Athlon 1600+ = Actually runs at 1.40 GHz 
AMD Athlon 1700+ = Actually runs at 1.47 GHz 
AMD Athlon 1800+ = Actually runs at 1.53 GHz 
AMD Athlon 1900+ = Actually runs at 1.60 GHz 
AMD Athlon 2000+ = Actually runs at 1.67 GHz 
AMD Athlon 2100+ = Actually runs at 1.73 GHz 
AMD Athlon 2200+ = Actually runs at 1.80 GHz 
AMD Athlon 2400+ = Actually runs at 1.93 GHz 
AMD Athlon 2500+ = Actually runs at 1.833 GHz 
AMD Athlon 2600+ = Actually runs at 2.133 GHz 
AMD Athlon 2700+ = Actually runs at 2.17 GHz 
AMD Athlon 2800+ = Actually runs at 2.083 GHz 
AMD Athlon 3000+ = Actually runs at 2.167 GHz 
AMD Athlon 3200+ = Actually runs at 2.20 GHz 

In choosing different manufacturers and models, the CPU would generally be dictated by the way you intend to use your computer. AMD CPUs are generally less expensive than Intel CPUs of the same clock speed but there are great differences in the CPU architecture. Intel Pentium 4 is specifically designed to optimise clock speed while the number of calculations per cycle is reduced. Therefore, benchmark tests of the speed of the AMD Athlon XP 3000+ is approximately the same as Intel Pentium 4 3.2GHz. Most gamers prefer AMD CPUs because of cheaper price for a faster speed, however, graphic designers and professionals prefer Intel CPUs due to their Hyper Threading technology.

You may wish to purchase a high end AMD64/emt64 processor, which provides support for 64-bit operating system (eg. Windows XP Professional 64-bit Edition). A 64-bit system is very efficient in handling large amounts of RAM. A 32-bit system efficiency drops beyond about 512 to 864MB of RAM, and becomes significantly less efficient beyond 4GB of RAM. Most processors for gaming range in about the 2.8Ghz-3.2Ghz

A 64-bit processor is currently an expensive investment as most applications run on the 32-bit system. However, there is no doubt that the 32-bit system would gradually be replaced by the 64-bit system when the prices fall over a few years time. It is unlikely that the 64-bit system would completely replace the 32-bit system within 5 years but Linux users might find a great improvement in speed when a 64-bit processor is used.

Smaller processors are generally preferred for overclocking, as they run cooler, and can achieve higher clock speeds. Retail CPU's come in a package containing a HSF (Heat Sink Fan), instructions, and a warranty, often 3 years. OEM CPUs do not include these.

The current CPU speeds and advantages change frequently, so for up-to-date comparisons, you may want to check a website that specializes in Hardware reviews, such as Tom's Hardware Guide or Anandtech. A good, current (as of 14 February 2006) beginner's explanation can be found at [1]

CPU Cooling

CPU cooling is very important and should not be overlooked. A less than average CPU temperature prolongs CPU life (up to more than 10 years). On the other hand high CPU temperatures can cause unreliable operation, such as computer freezes, or slow operation. Extremely high temperatures can cause immediate CPU destruction by melting the materials in the chip and changing the physical shape of the sensitive transistors on the CPU. Because of this, never switch on the computer if your CPU has no cooling at all. It is an extremely stupid thing to do, the scenario of 'I'll just test whether my CPU works!' as by doing so, you would find that the CPU fries in less than 5 seconds and you will be off to buy a new one.

Most CPU installations use forced-air cooling, but convection cooling and water cooling are also options. For traditional forced-air cooling, the heat sink and fan (HSF) included in most retail CPUs is usually sufficient to cool the CPU at stock speed. Overclockers might want to use a more powerful aftermarket fan, or even try water cooling because they need additional cooling ability given the increased heat of overclocking.

HSFs with decent performance are usually copper-based. The cooling effect is enhanced if the HSF has heatpipes. Silent (i.e. Fanless) HSFs are there to provide users a nearly silent cooling.

Many retail heatsink+fan units have a thermal pad installed, which transfers heat from the CPU to the fan helping diffuse the heat created by the CPU. This pad is usable only once. If you wish to remove the fan from another CPU so that you can use it on your new one, or need to take it off for some reason, you will need to remove it, and apply a thermal paste or another thermal pad. Note that some of the cheaper pads can melt in unexpected heat and may cause problems and potentially even damage if you are overclocking. In either case, thermal paste is usually more effective, just harder to apply. If you plan to do any high performance computing, or removing and replacing the HSF, often thermal paste is suggested. If you are planning a long term installation a thermal pad is suggested. Non-conductive thermal pastes made up of silicon are the cheapest and safest.

Silver-based thermal pastes sometimes perform better than normal thermal pastes, and carbon-based ones perform better still. When applied improperly both can be conductive, causing electrical shorts upon contact with the motherboard. A thin properly-applied layer will usually prevent this problem, though some pastes can become runny when they get hot. Users should also beware that many "silver" thermal pastes do not actually contain any silver metal.

For quiet operation, start with a low-heat (low number of watts) CPU. Processors made by VIA, such as the VIA C3, tend to produce low amounts of heat. The Pentium M gives performance that is on par with many of the desktop processors, but gives off more heat than the Via processors. You can also underclock your CPU, giving up some unneeded performance for some peace and quiet. Another option is to choose a large copper heat sink with an open fin pattern. However, true fanless operation is difficult to achieve in most case designs. You can position a case fan to blow across the heat sink, or mount a fan on the heat sink. With either choice of fan placement, choose a large and slow fan over a small and fast fan to decrease noise and increase air flow.

Some low-noise CPU cooling fans require special mounting hardware on the motherboard. Be sure that the cooling fan you choose is compatible with your motherboard.

Motherboard

It cannot be stressed more that the motherboard is the MOST important part of your computer. It is worth investing in a decent motherboard rather than a CPU (although if financially acceptable, both) as your motherboard is what connects different parts of the computer together. In addition, the difference between a cheap and a nice motherboard is typically around $100 US. A good motherboard allows a modest CPU and RAM to run at max efficiency whereas a bad motherboard causes high-end products to run only modestly, a motherboard should go into the $300 U.S. range for maximized capabilities.

There are 6 things one must consider in choosing a motherboard, CPU Interface, Chipset, IDE or SATA support, Expansion Slot Interfaces and Other Connectors.

CPU Interface The CPU interface is the "plug" that your processor goes into. For your processor to physically fit in the motherboard, the interface must be an exact match to your processor. Intel currently has two mainstream formats, the older Socket 478 (which is gradually being phased out) and the newer Land Grid Array 775, which supports higher end CPU with HT technology due to its more efficeint transfer rate. AMD currently uses two sockets, 754 and 939. Socket 754 is being aimed at the value market, with all new performance CPUs being released for Socket 939.

Formfactor You must choose a case that your motherboard can fit inside of. A micro-ATX motherboard will do, mostly because it can fit, and it fits many type of CPU sockets.

Chipset Chipsets are also important as it determines the efficiency of RAM and Expansion slots Intel 915 supports upto 533MHz DDRII RAM Intel 925 supports upto 600MHz DDRII RAM

The functions of BIOS is highly important. Some BIOS features crash proof functions essential for updating the firmware. Other motherboards allow BIOS control of overclocking of CPU, RAM and Graphics card which are much more stable and safer for overclocking. Newer BIOS have temperature controls, and functions that shut down the computer if the temperature gets too high.

IDE (ATA) or SATA interface Older PCs have the two IDE interface which are parallel 44 pin connectors but as the motherboard cannot access two devices connected on the same IDE port simultaneously, this has caused a drawback in speed of hard drives and DVD-drives. The newer serial ATA (SATA) interface has 4 separate slots that allow independent access and thus increases the speed of which hard drives work.

Expansion Slot Interfaces Old motherboards have the following slots:

• AGP - for graphics cards (ranging from AGP 1x, 2x, 4x and 8x)
• PCI - for expansion cards and obsolete low end graphics cards

...Note: Some graphics cards that run on PCI interfaces are not always obsolete. ATI still manufactures PCI graphics cards, but for better performance try a card supporting PCI-Express. AGP is not a good idea, becuase it requires specific steps to set up, and the drivers, if not updated, do not support the card.

Due to the evolution of new graphics cards on the serial PCI-Express Technology, current newer motherboards have the following connections:

• PCI-Express 16x - for mainstream graphics cards (4 times speed of AGP 8x)
• PCI-Express 1x - for faster expansion cards (replacing older PCI)
• PCI - for use of old expansion cards (would be phased out)

Older AGP 8x graphics cards are generally being phased out for PCI-Express 16x, as the speed and efficiency is about 4 times that of the AGP 8x technology. Old PCI cards are either now built into the motherboard (for sound cards, LAN cards, IEEE 1394 firewire and USB 2.0 interfaces) or becoming PCI-Express variants.

Other Connectors Some considerations for other connectors and expansions include

• USB - the number and version of USB connectors (USB 1.0, 1.1 or 2.0)
• On-Board Sound Card - Stereo, 3.1, 5.1, 6.1, 7.1, 8.1
• On-Board Graphics Card (Phasing Out)
• On-Board Base 100 LAN Card
• Serial COM or Parallel Printer Ports
• On-Board IEEE 1394 Firewire

I would suggest at least 6 USB 2.0 ports for high speed access. On-Board Graphics cards are generally becoming obsolete as they cannot match the newer PCI-Express 16x technology, especially for gaming where high cooling and efficiency is required. USB ports sometimes can come bundled into the front of your computer case for easier access. (Most on-board graphics chipsets are Intel's Extreme Graphics (2), a very obsolete graphics interface.)

Most motherboards also come with onboard sound. Onboard sound is more than enough for most users, although if you are particular about audio quality or plan to use your computer to record high-end audio, you may prefer to use a dedicated sound card (preferably PCI-Express 1x). Some high-end motherboards support on-board 5.1 Channel Dolby surround sounds so this may also be a consideration.

Onboard graphics are very acceptable for anyone not playing 3D games or using 3D graphics applications. Onboard graphics will use a small amount of system RAM as graphics memory (often called shared memory). Purchasing a motherboard with a built-in graphics card is an easy way to save money for an office computer.

If you want gigabit Ethernet, you should purchase a motherboard with the feature built in. By being built into the motherboard, it will have a faster link to all your components than it would through a PCI expansion card. Also, if you'd like to import Digital Video (DV) onto your system, many motherboards offer onboard FireWire ports.

If you are upgrading an older computer, keep in mind the motherboard's number and type of expansion board slots.

RAM (Random Access Memory)

The amount of RAM you use is dependent on the purpose that you want to use it for. Older versions of Windows and Linux will run comfortably, though slowly at times, on 128 MB. Some newer operating systems such as Windows XP require 256MB of RAM to run comfortably. Many people now have 512 MB or more for better performance. Users of modern games and graphics software, or people who may wish to host Internet services such as a Web site, may want 1 GB or more.

Another thing to consider when choosing the amount of RAM for your system is your graphics card. Most motherboard-integrated graphics chips and PCI Express graphics cards marketed with the "Turbo Cache" feature will use system memory to store information related to rendering graphics; this system memory is generally not available at all to the operating system. On average, these graphics processors will use between 16MB and 128MB of system memory for rendering purposes.

The actual type of RAM you will need will depend on the motherboard and chipset you get. Most current motherboards use DDR (Double Data Rate) RAM. The Intel 915/925 chipsets use DDR2 RAM. Chipsets that use dual-channel memory require you to use two identical (in terms of size and speed) sticks of RAM. Your RAM should usually operate at the same clock speed as the CPU's Front Side Bus (FSB). Your motherboard may not be able to run RAM slower than the FSB, and using RAM faster than the FSB will simply have it run at the same speed as your FSB. Buying low-latency RAM will help with overclocking your FSB, which can be of use to people who want to get more speed from their system.

If you are upgrading from an existing computer, it is best to check with a user group to see if your machine requires specific kinds of RAM. Many computer OEMs, such as Gateway and HP, require custom RAM, and generic RAM available from most computer stores may cause compatibility problems in such systems.

RAM have different bandwidths, ie 400, 533, 600, 733, 800, the current trend is moving from DDR2-400 RAM to DDR2-533 RAM as it is more efficient. Higher end models are very expensive unless you find it worth the investment.

Labeling of RAM

RAM are labelled by its Memory Size (In MB) and clockspeed (or bandwidth).

• SDRAM (Synchronous Dynamic RAM) is labeled by its clock speed in megahertz (MHz). For example, PC133 RAM runs at 133MHz. SDRAM is nearly obsolete as nearly all motherboards have withdrawn support for SDRAM. It is now superceded by the more efficient DDR RAM.
  • 128MB SD-133 = 128MB PC133 RAM

• DDR RAM can be labeled in two different ways. It can be labeled by approximate bandwidth; as an example, 400MHz-effective DDR RAM has approximately 3.2GB/s of bandwidth, so it is commonly labeled as PC3200. It can also be labeled by its effective clock speed; 400MHz effective DDR RAM is also known as DDR-400. There is also DDR and DDR2 labelled as PC and PC2.
  • 256MB DDR-400 = 256MB PC 3200 RAM
  • 256MB DDR2-400 = 256MB PC2 3200 RAM

DDR RAM has two versions DDR (also DDRI) and DDR2 (or DDRII)

• DDR supports DDR-100, DDR-200, DDR-300, DDR-400 (mainstream) and DDR-533 (rare)
• DDR2 supports DDR-400, DDR-533 (mainstream) and rare/expensive DDR-600, DDR-733, DDR-800, DDR-933, DDR-1066

Hard Drive

Things to consider when shopping for a hard drive:

• The Interface of a drive is how the hard drive comunicates with the rest of the computer. The following hard driver interfaces are avalible:
  • IDE cables can be distinguished by their wide 40-pin connector, coloured first-pin wire, and usually white "ribbon" style cables. This technology is rapidly deteriorating, as it cannot keep up with the increasing speed of current hard drives. IDE based hard drives do not exceed 7,200 RPM.
  • SATA SATA drives reach up to 10,000 RPM. If you want Serial ATA, you will either need to purchase a motherboard that supports it, or purchase a PCI card that will allow you to connect your hard drive.
  • SCSI Although SCSI is more expensive and less user friendly it is usualy worthwile on high performance workstations and servers. Few consumer desktop motherboards built today support SCSI, and for building a new computer, the work needed to implement it may be outweighed by the relative simplicity and performance of IDE and SATA.
  • USB or IEEE1394 can be used for connecting external drives. An external drive encolsure can convert an internal drive to an external drive.
• Formfactors:
  • 3.5 inches is usally used in desktops
  • 2.5 inches is usually used in laptops
• Capacity - As a rule-of-thumb minimum, you will need a hard drive capable of holding at least 20GB, although the largest drives available on the market can contain 500GB. Few people will need disks this large - for most people, somewhere in the range of 80-200GB will be sufficient. The amount of space you will need can depend on many factors, such as how many high-end games and programs you want to install, how many media files you wish to store, or how many high-quality videos you want to render. It is usually better to get a hard drive with a capacity slightly larger than you anticipate using, in case you need more in the future. However, should you run out of space, you may add an additional hard drive if you have any free IDE or Serial ATA connectors, or through an external interface, such as USB or FireWire.
• Rotational Speed is the speed that the hard drives platters spin at. However drives above 7,200 RPM usually have limited capacity, and a much higher price than 7,200RPM drives of the same capacity, making drives above 7,200RPM not ideal for the desktop.
• One additional consideration when purchasing a hard drive should be the drive warranty. Many manufactures offer warranties ranging from 30 days (typically OEM) up to five years. It is well worth spending an extra few dollars to extend the drive warranty as long as possible.

Secondary Components

These components are important to your computer, but are not as central and necessary as the Core Components.

Video Output

For a computer to use a display for monitoring it will need some form of video card into which a display can be pluged. The majority of home and office computers, which predominatly use 2D graphics for office applications and web surfing can use an 'onboard' or integrated graphic processor which will be included on most low to mid range mainboards. For building a computer for gaming, or 3D modelling, a good quality graphics card will be needed.

Graphics Card

Currently, two companies dominate the 3D graphics accelerator market nVIDIA and ATI. nVIDIA and ATI build their own graphics products, and license their technologies to other companies. Each brand's similar models have comparable performance levels, and each brand has its own supporters. Video cards have their own RAM, and many of the same rules that dominate the motherboard RAM field apply here: the more RAM, and the faster it is, the better the performance will be. Most applications require at least 32MB of video RAM, although 128MB is rapidly becoming the new standard. On the other end, 512MB video cards top the consumer end of the video card market. As a rule of thumb, if you want a high end video card, you need a minimum of 128MB of video memory -- preferably 256MB. Don't be fooled, though; memory is only part of the card and the actual video processor is more important than the memory. It is important to understand that an integrated graphics card uses the system's RAM, and relies heavily on your system's CPU. This will mean slow performance for graphic-intensive software, such as games.

It is generally better to choose your video card based on your own research, as everyone has slightly different needs. Many video card and chip makers are known to measure their products' performances in ways that you may not find practical. A good video card is often much more than a robust 3D renderer; be sure to examine what you want and need your card to do, such as digital (DVI) output, TV output, multiple-monitor support, built-in TV tuners and video input. Another reason you need to carefully research is that manufacturers will often use confusing model numbers designed to make a card sound better than it is to sell it better. For example, the Geforce 4 MX series of cards claim to be a "Geforce 4," however, the actual processor is closer to a Geforce 2, only more powerful, meaning that these cards actually lack many features available even to the Geforce 3 series. However, when these cards were first produced, they were considerably cheaper than a real Geforce 4 (the TI series) making them an ideal choice if you were more interested in working on a spreadsheet than in playing games. For this sort of reason, you have to carefully pick your card depending on your needs. TV outputs can easily be adapted to your computer by using a DVI - Component Video cable.

Interface

There are four different graphics card interfaces: integrated, PCI, AGP and PCI-Express.

Most retail computers will ship with an integrated graphics card. This means that if you are looking at playing games you will need to upgrade. Most mainboards that have integrated graphics will also have one of the other three interfaces so it isn't hard to place a new card to suit your needs if the need ever arises.

Old video cards use the standard PCI slots that are now obsolete due to limited speed and memory. PCI cannot transfer data very quickly, so a system with such a card will often seem to "jump" or halt for short periods when data is being transfered. These cards are needed for a few rare systems lacking an AGP slot (usually low end desktop systems designed to be cheap.) They are also useful for adding aditonal video cards to a system.

Most video cards bought in the last 2 years are of the AGP standard. There are 4 different speed and bandwidths of AGP, 1x, 2x, 4x and 8x. While 8x is the fastest and most common for high end products, the true performance of your AGP card is limited by the lower AGP value of your graphics card and motherboard. For example, an AGP 8x card on a 4x motherboard can only run at up to 4x. AGP will be phased out and there will not be an AGP 16x due to technical limitations, and size necessarily.

The newest trend in graphics card is the PCI-Express system that supports upto 16x speeds. This is new technology and is generally more expensive but it runs at higher speeds. Some newer graphics cards come in both AGP and PCI-E 16x models, such as the Radeon x800 and the GeForce 6800 series. The newest graphics card, the GeForce 7800, is only made for the PCI-E 16x. (Most motherboards have one PCI-E 16x while plenty of PCI-E 1x slots... so make sure you use the right one.) Motherboards with 2 PCI-Express 16x slots can combine the power of 2 video cards. However, you will have to match the video cards to a motherboard supporting the 2 video cards dual card implementation, and use 2 video cards that are the same and that support dual video cards.

CD/DVD

Optical drives have progressed a long way in the past few years, and you can now easily purchase DVD writers that are capable of burning 9GB of data to a disk for an insignificant amount of money. Even if you don't plan on watching or copying DVDs on your computer, it is still worth purchasing a burner for their superior backup capabilities.

When purchasing a DVD writer, you will want one that is capable of burning both the '+' and '-' standards, and they should also be Dual Layer compatible. This will ensure that you can burn to almost all recordable DVDs currently on the market (the other major format, DVD-RAM is almost unused, for the most part, so don't worry about it).

Floppy Drive

Though generally not needed, floppy drives are often installed anyway. Floppy drives have been made obsolete in recent years by devices such as USB "Thumb Drives" and CD writers. Floppy drives are sometimes required for BIOS updates and exchanging small files with older computers. Floppy drives block air movement with wide cables, and can make computers set to check the drive take longer to start (most have an option in their bios to disable this.) The drives and disks are also notoriously unreliable. One option to overcome the cable problem and to make it easier to install is to buy an external USB floppy drive. These are potentially a little bit faster and can be plugged into a different system (such as a laptop without a floppy drive.) However, not all systems support booting from a USB floppy drive -- most notably older motherboards. Most newer systems do now though. A USB floppy drive is considerably more expensive and since floppy drives are not needed much anymore, this is rarely a useful option. You can easily get a thumb drive holding more than 50 times as much as one floppy disk for the same price as a USB floppy drive.

Sound Card

Most motherboards have built-in sound features. These are often adequate for most users. However, you can purchase a good sound card and speakers at relatively low cost - a few dollars at the low end can make an enormous difference in the range and clarity of sound. Also, these onboard systems tend to use more system resources, so you are better off with a real soundcard for gaming.

Good quality in sound cards depends on a few factors. The digital-analog conversion (DAC) is generally the most important stage for general clarity, but it is a poorly measurable process. Reviews, especially those from audiophile sources, are worth consulting for this; but don't go purely by specifications, as many different models with similar specs can produce completely different results. Cards may offer digital (S/PDIF) output, in which case the DAC process is moved from your sound card either to a dedicated receiver or to one built into your speakers.

Sound cards made for gaming or professional music tend to do outstandingly well for their particular purpose. In games various effects are oftentimes applied to the sound in real-time, and a gaming sound card will be able to do this processing on-board, instead of using your CPU for the task. Professional music cards tend to be built both for maximum sound quality and low latency (transmission delay) input and output, and include more and/or different kinds of inputs than those of consumer cards.

Modem

A modem is needed in order to connect to a dial up internet connection. A modem can also be used for faxing. Modems can attach to the computer in different ways, and can have built-in processing or use the computer's CPU for processing.

Modems with built-in processing generally include all modems that connect via a standard serial port, as well as any modems that refer to themselves as "Hardware Modems". Software Modems, or modems that rely on the CPU generally include both Internal and USB modems, or have packaging that mentions drivers or requiring a specific CPU to work.

Modems that rely on the CPU are often designed specifically for the current version of Windows only, and will require drivers that are incompatible with future Windows versions, and may be difficult to upgrade. Software Modems are also very difficult to find drivers for non-Windows operating systems. The manufacturer is unlikely to support the hardware with new drivers after it is discontinued, forcing you to buy new hardware. Most such modems are internal or external USB, but this is not always the case.

Modems can be attached via USB, a traditional serial port, or an internal card slot. Internal and USB modems are more easily autodetected by the operating system and less likely to have problems with setup. USB and serial port modems often require an extra power supply block.

Gaming modems are normal modems that default to having a low compression setting to reduce lag, but are generally no longer used by gamers, who prefer broadband connections.

Ethernet Card

An ethernet card is required in order to connect to a local area network or a cable or DSL modem. These typically come in speeds of 10mbps, 100mbps, or 1000mbps (gigabit); these are designated as 10Mbps, 10/100Mbps, or 10/100/1000Mbps products. The 10/100 and 10/100/1000 parts are most commonly in use today. In many cases, ethernet will be built into a motherboard. Otherwise, you will have to purchase one - these typically are inserted into a PCI slot. For 10/100/1000Mbps ethernet, it is recomended that you use one built into your motherboards chipset.``

Peripherals

Your computer and you interact through the peripherals. The keyboard and monitor are pretty much the barest minimum you can go with and still be able to interact with your computer. Your choice in peripherals very much depends on personal preference and the complexity of the interactions you intend to have with your computer.

Keyboard & Mouse

When choosing a mouse, there is generally no reason to not choose an optical mouse. They are considerably lighter (and as such, reduce RSI) as they have no moving parts, they are much better at smoothly tracking movement, and they don’t require constant cleaning like ball mice (though it may be wise to brush off the lens with a q-tip or other soft tool on occasion.) Make sure that you spend money on a decent-quality mouse made by companies such as Microsoft or Logitech, as lower-end optical mice will skip if moved too fast. Mice of medium-to-high quality will track the movement almost flawlessly.

Although three buttons are generally enough for operating a computer in normal circumstances, extra buttons can come in handy, as you can add set actions to extra buttons, and they can come in handy for playing First Person Shooter games. One thing to note is that with some mice those extra buttons are not actually seen by the computer itself as extra buttons and will not work properly in games. These buttons use software provided by the manufacturer to function. However, it is sometimes possible to configure the software to map the button to act like a certain keyboard key so that it will be possible to use it in games in this manner.

Wireless keyboards and mice do not have a hugely noticeable delay like they once did, and now also have considerably improved battery life. However, gamers may still want to avoid wireless input devices because the very slight delay may impact gaming activities -- though some of the higher end models have less troubles with this -- and the extra weight of the batteries can be an inconvenience.

Printer & Scanner

For most purposes, a mid-range Inkjet Printer will be more than enough for most people, and you will generally want one that is capable of printing around 4800dpi, and you will also want it to be able to print out fairly quickly. When choosing a printer, always check how much new cartridges cost, as replacement cartridges can often outweigh the actual printer's cost in less than a year. Of course, double check extra information about the printer you are interested in (for example, Epson has protection measures that make refilling your own ink cartridges more difficult because the printer will not see the cartridge as full once it is used up).

For office users that plan to do quite a bit of black and white printing buying a black and white laser printer is now an affordable option, and the savings and speed can quickly add up for home office users printing more than 500 pages a month.

Scanners are useful, especially in office settings, they can function with your printer as a photocopier, and with software can also interact with your modem to send Faxes. When purchasing a Scanner, check to see how "accessible" it is (does it have one-touch buttons), and check how good the scanning quality is, before you leave the store if possible.

Finally, "Multi-Function Centres" are often a cost-effective solution to purchasing both, as they take up only one port on your computer, and one power point, but remember that they can be a liability, since if one component breaks down, both will need to be replaced.

Display

When choosing a display for your computer, you have two key choices of technology: the Cathode Ray Tube (CRT) screen, or an LCD screen. Both technologies have their advantages and disadvantages: CRTs are generally preferred by gamers and graphic artists, for both the price at which they can be bought and their generally superior response times, but this is offset by the added size and weight that a large screen requires. LCDs are generally more expensive than CRTs, but high-end models are generally preferred for tasks which need higher definition, such as movie editing, and are also popular amongst people with little-to-no desk space, as they do not need as much space as a similarly-sized CRT.

LCD Panels

Liquid Crystal Displays (LCD's) have the advantage of being a completely digital setup, when used with the DVI-D digital connector. When running at the screen's native resolution, this can result in the most stable and sharp image available on current monitors. Many LCD panel displays are sold with an analog 15-pin VGA connector or, rarely, with an analog DVI-I connector. Such displays will be a bit fuzzy, and are generally best avoided for a similarly-sized CRT. If you want an LCD displays, be sure to choose a digital setup if you can; however, manufacturers have chosen to use this feature for price differentiation. The prime disadvantage of LCDs is "dead pixels", which are small failing areas on your monitor, which can be very annoying, but generally aren't covered under warranty - this can make purchasing LCD displays a financial risk. LCDs are generally OK for fast-paced gaming, but you should be sure that your screen has a fairly fast response time (of 12 ms or lower) if you want to play fast games. Nearly all flat panels sold today meet this requirement, some by a factor of 3. When picking an LCD, keep in mind that they are designed to display at one resolution only, so, to reap the benefits of your screen, your graphics card must be capable of displaying at that resolution. That in mind, they can display lower resolutions with a black frame around the outside (which means your entire screen isn't filled), or by stretching the image (which leads to much lower quality). Running at a higher resolution than your monitor can handle will either make everything on the screen smaller, at a significant quality drop, or will display only a part of the screen at a time (which can be annoying).

Cathode Ray Tube Displays

The other key type of display is the CRT or Cathode Ray Tube display. While CRT technology is older it often outperforms LCD technology in terms of response times, color reproduction, and brightness levels, although LCD displays are quickly catching up. There are two types of CRT displays, shadow mask and aperture grill. An aperture grill display is brighter and perfectly flat in the vertical direction, but is more fragile and has one or two mostly-unnoticeable thin black lines (support wires) running across the screen. CRTs are generally 2-4 times as deep as similarly-sized LCDs, and can weigh around 10 times as much, but this normally isn't a concern unless you will be moving your computer a lot. If you purchase a CRT display over the internet, shipping is much quicker, which is good for gaming, however, can cause headaches in some people at lower rates, so it may be ideal to pick a screen offering higher update frequencies at whichever resolutions you intend to use. Most people who have problems with low frequencies (60Hz) find it preferable to have at least 80Hz at the intended resolution. Some won't be bothered by this at all however.

Note that sometimes the CRTs with a flat screen instead of curved are called "flat screens" so this is not to be confused with the term "flat panel" used to refer to LCDs.

Speakers

Computer speaker sets come in two general varieties; 2/2.1 sets(over a wide range of quality), and "surround", "theater", or "gaming" with four or more speakers, which tend to be significantly more expensive. Low-end speakers usually suffer from low bass response or having no amplification, both of which make a huge difference in sound. Powered speakers with separate sub-woofers usually cost only a few dollars more and make a significant difference. At the higher end, one should start to see features like standard audio cables (instead of manufacturer-specific ones), built in DACs, and a separate control box. The surround sets are usually identical to the 2.1 set of a manufacturer, just with more speakers, which can be useful for gaming or movie watching. 5.1 and 7.1 support are becoming standard now, however, it is still necessary that you ensure your sound hardware is capable of 5.1/7.1 before buying a speaker system for this. If you have a lot of money you want to spend on audio, it may be wiser to avoid the computer speaker market entirely and look into piecing together a set of higher-end parts. The computer speaker market tends to start pumping up wattage without making any quality improvement - you can usually get more volume, that's all. If you are buying a speaker system designed for PCs, research the systems beforehand so you can be certain of getting one that promises clarity rather than just simple wattage. (Note: speaker power is usually measured in RMS Watts. However, some cheap speakers use a different measure, PMPO which appears much higher.)

Headphones can offer good sound much more cheaply than speakers, so if you are on a limited budget but want maximum quality they should be considered first. There are even headphones which promise surround-sound, though opinions on this are usually not good.

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