Description
What To Look For
Buying Tips
Recommendations

Already know what a CPU is and what to look for? Then skip to the Recommendations. 

What To Look For:

• One basic thing to look for in a CPU, the GHz rating.  Obviously, the higher, the better.  If there is one part you are going to splurge on for your computer, make it the CPU.  A good rule to go by is getting a CPU that is a couple steps below the top speed CPU.  You won't notice much of a performance difference, and you'll save a lot of money since the very fastest CPUs are significantly overpriced.
• Bus Speed is another very important thing to look for (see Glossary for definition). Currently 200 MHz is the most common bus speed (although this is often reported as 400 MHz or 800 MHz as it is dual or quad pumped). Many CPUs still run at 166 or slower though.
• Internal Cache is the quick access memory that is on the CPU to hold recent data. This memory is very important in speeding things up. When comparing CPUs, you may want to look at how much cache the CPU has. Be warned: Intel's Celeron CPUs have very little cache memory - that's why they're cheaper! Oddly enough, in some applications it performs quite well, but other applications may cause it to perform very slowly. 
• Another thing to consider with CPUs is the micron size of the CPU die. Smaller sizes result in cooler operation and thus allow for higher clock speeds. 

Buying Tips:

• So, considering the CPU is the most important part, should you buy the fastest CPU available? Not necessarily. There are two things to consider here. First of all, the highest speed CPU is usually way overpriced.  One or two steps down will get you a CPU that will perform just as well to the human eyes, yet cost much less.  That is probably the best strategy.  A second strategy you may want to consider is to buy a slowish, cheap CPU to start.  Purchase the slow CPU with the intention of upgrading your CPU in about a year or less.  Then, after that time has passed, you can probably buy a CPU that would be faster than you could have gotten before, but now it would cost much less.  Here's an example with fictional figures and CPUs:
  Buy a 2.6 GHz CPU for $150 when the top of the line is 3.2 GHz for $500.  After about a year, buy a 3.4 GHz CPU for about $150. Now, you got a faster CPU, but still saved $200 overall! Note, you might not encounter that wide of a range of CPU speeds that would all fit in the same motherboard.
  Related topic: Motherboard.
• Buy from a dealer you KNOW you can trust.  Why?  Simply because there is a rapidly spreading trend going around where some dealers are "remarking" their CPUs.  For example, they may take a 2.8 GHz processor, remark it and overclock it, and try to sell it as a 3.2 GHz processor in order to make more money off the CPU. Thus, the dealer is overclocking the CPU before you own it. You can check ResellerRatings.com for customer reviews of merchants.

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Recommendations