What makes a computer fast is a question that may have different answers for different people. If you are a business user with a large database, de-fragging your hard drive may make your computer faster. If you use your computer mainly for games, then video card memory may be the most important thing. If you keep many programs open and running at the same time, the RAM will be the key component.
CPU
1. The Central Processing Unit (CPU) is the most basic answer to what controls the speed of your computer. This is the brain of the computer attached to the motherboard and it processes data at a set rate. Usually, if you want a faster computer, you need a faster processor.
RAM
2. Although Random Access Memory (RAM) doesn't make your computer faster like a new CPU, it does allow more programs to be opened at once. This will allow the computer to complete more processes at the same time, giving you a faster computer.
Bus Speed
3. The bus is the data transport system on the motherboard that should be matched in speed by the CPU and the RAM. It transports data between all the devices on the computer. This has an impact on how fast data can arrive and therefore the perceived speed. Think of bus speed as a smooth, freshly paved multi-lane highway between the CPU and the RAM.
Video Memory
4. On most regular desktop computers, the video memory is a shared part of the RAM and a certain portion is dedicated to video processing. A video card with on-board memory can free up that RAM so it can be used in regular operations by the CPU. The more memory on the video card, the better it can process and render your games and graphics. This will keep the CPU from having to slow down and take time from other processes.
Hard Drive
5. The hard drive has the least impact on overall speed. There are drives that have faster data transfer rates than others, but unless everything else on the computer is vastly faster, you would never notice this. Usually, the hard drive can have a noticeable impact on speed when it is more than 75 percent to 80 percent full, or badly fragmented. If you store several gigabytes of files in one folder like My Documents, this can slow down opening files and folders. Regularly de-fragging your hard drive, un-installing old and unneeded software and culling through old files will help these issues and reduce any impact on speed.
Viruses
6. Every computer faces the threat of slow performance due to viruses and malware. Keep a good, updated anti-virus and anti-malware program to keep your computer clean. Viruses, spyware and malware can install unwanted files and conflicting processes, which eat up a computer's processing speed and keep your machine from running fast.
Read more: What Makes Computer Fast? eHow.com http://www.ehow.com/about_5394578_computer-fast.html#ixzz1E3OeohTD
