The CPU is the centerpiece and nerve center of your system. When building a PC, you start by choosing a processor and work your way out from there. What chip you buy dictates the maximum speed of your RAM and what type of motherboard you can use. Your motherboard purchase then dictates what sort of graphics card you can buy, and so on.

Speed Thrills
Sure, it sounds sexy to tell all your friends that you have the fastest chip on the market in your custom machine, but do you need it? The AMD FX-60 (pictured here) is a blazing dual-core 64-bit workhorse; it would be complete overkill to use this chip to run Microsoft Excel and publish the canasta-club newsletter.

Pick Your Poison
Intel and AMD make a huge variety of CPUs that run at a multitude of different speeds. One of the coolest things about building a PC is being able to select the exact chip to fit your needs. If you are going to run several large multimedia appli-cations at the same time, you might want to pick up one of the new dual-core chips. If you're trying to save a few bucks, try a lower-priced Sempron or Celeron.

Socket Something or Other
Hundreds of pins and holes make up the the socket— the interface between a CPU and a motherboard. Intel and AMD use different sockets, and since the sockets have evolved with the chips, newer CPUs won't fit older interfaces. Double-check yours.

Stats to Watch:

Speed: From 1.0 to 3.8 GHz, faster's always better.

Socket: Match the CPU's interface to your motherboard.

Front-side bus: Determines the maximum memory speed.

Click here to see the CPU Install Guide