CPU - Central Processing Unit

The brain of the computer. A lot of people like to call the entire computer case the CPU, but actually, the CPU is a tiny chip connected directly to the motherboard, with a big fan connected directly to it. Without the fan, the CPU would burn up very quickly.

There are two primary brands of CPU on the market right now, Intel & AMD. A better of the two is hard to state, but you can check Toms Hardware for more in depth hardware reviews.

One thing to note about CPU's is that you can't just slap any CPU into any Motherboard. The Motherboard must support your specific CPU, which can make upgrades very hairy, so typically, if you're going to upgrade one, it's a good idea to upgrade the other. See more on Motherboards on the Motherboard page.

There are also two different types of CPU's, socket and slot. Socket snaps directly into the motherboard, with a fan directly attached, while slot has a casing which holds the CPU, with a fan connected to the casing. Again, there really is no better of the two, but Socket is becoming more common, and is generally easier to keep cool, which is a BIG factor in CPU's at higher speeds.

CPU speeds are rated in Megahertz (Mhz), up to 1000, then they are referred to as Gigahertz (Ghz). One major misconception regarding CPU's is that the bigger the number (the megahertz/gigahertz), the faster the CPU. While this is generally true, there are several other factors that effect the overall speed of the CPU.

Front Side Bus - Regulates the speed of communication between the Ram and the CPU

Onboard Cache - Comparable to Ram, except used strictly by the CPU to speed up calculations

So the next time you're shopping for CPU's, remember to not only look at the CPU speed, but check out the other factors most people don't generally notice. When buying a CPU, it's very important to know what you need it for. Most basic users only need internet and some word processing and basic picture editing. Using Windows XP (since it's the most common home Operating System right now) 2.0 Ghz should be your minimum. This speed is just right for these basic functions, and should be fast enough to last a while, and most of all, it is very cheap.

One thing to note here is that the price difference between the 2.0 Ghz and the upper 2.x Ghz CPU's (like 2.6 or 2.9) is so slight that you might be better off to get the one slightly higher to last longer over time.

I do NOT suggest buying the fastest cpu on the market, ever.. simply because what you pay six hundred dollars or more for now, will be only a few hundred dollars in a couple of months, and this will always be true as long as cpu speeds keep increasing.