CPU

Contents

Description
What To Look for
Recommendations

Description:

So what's a CPU? It stands for Central Processing Unit. Many users erroneously refer to the whole computer box as the CPU. In fact, the CPU itself is only about 1.5 inches square. The CPU does exactly what it stands for. It is the control unit that processes all* of the instructions for the computer. Consider it to be the "brain" of the computer. It does all the thinking. So, would you like to have a fast or slow brain? Obviously, the answer to this question makes the CPU the most important part of the computer. The speed here is the most significant. The processor's (CPU's) speed is given in a MHz or GHz rating (see Glossary). 3 GHz is roughly 3,000 MHz.

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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.
Recommendations:
• Intel's Pentium IV and AMD's Athlon 64 CPUs are currently the CPUs of choice for most users. The Pentium IV Prescott has 1 MB cache instead of the original Pentium IV's 512 k cache. The Athlon 64 CPUs differ from the Athlon XP in that they are 64-bit CPUs (AMD has the advantage over Intel here, since Intel's Pentium IV CPUs are not 64-bit) and some offer 1 MB cache. 64-bit CPUs will be needed to run Windows XP 64-bit and other 64-bit applications. It's nice to be able to buy a CPU now that will work with both 32-bit and 64-bit later (the Athlon 64). Intel reports their CPUs in real MHz speed (although they're about to go to a ranking scheme also). AMD reports theirs in a performance ranking format, compared to Intel's CPUs. So for example, an Athlon XP 3200+ is supposed to perform on par with a 3.2 GHz Intel Pentium IV. Here's a handy table of their real speeds. You may find it confusing because the "faster" CPUs sometimes run at slower clock speeds. That is because the core has been improved and/or the bus speed is higher and/or there is more cache memory. Older CPUs are not included, and I didn't include AMD's Opteron CPUs because they are meant for servers and not as popular with home users:
Athlon 64 FX 53 2.4 GHz / 1 MB cache
Athlon 64 FX (or FX 51) 2.2 GHz / 1 MB cache
Athlon 64 3400 2.2 GHz / 1 MB cache
Athlon 64 3200 2 GHz / 1 MB cache
Athlon 64 3000 2 GHz / 512 k cache
Athlon 64 2800 1.8 GHz / 512 k cache
Athlon XP 3200 / 400 bus 2.2 GHz / 512 k cache
Athlon XP 3200 / 333 bus 2.2 GHz / 512 k cache
Athlon XP 3000 / 400 bus 2.1 GHz / 512 k cache
Athlon XP 3000 / 333 bus 2.167 GHz / 512 k cache
Athlon XP 2800 / 333 bus 2.08 GHz / 512 k cache
Athlon XP 2700 / 333 bus 2.167 GHz / 256 k cache
Athlon XP 2600 / 333 bus 1.9 GHz / 512 k cache
Athlon XP 2600 / 266 bus 2.08 GHz / 256 k cache
Athlon XP 2500 / 333 bus 1.83 GHz / 512 k cache
Athlon XP 2400 / 266 bus 2.0 GHz / 256 k cache
Athlon XP 2200 / 266 bus 1.8 GHz / 256 k cache

• Intel vs AMD. These two companies have been fighting it out for many years. Which one is better? That is a tough decision to make, and much of it depends on the current time period. AMD may have the crown for awhile, then Intel steals it, and it goes back and forth. AMD is usually cheaper, but they had a history of relatively unstable CPUs (or unstable motherboards that go with them). This has improved significantly in the past couple of years, and I now consider Intel and AMD to be equally stable. Which do I recommend? It's really up to you. If you want to save a little, get AMD now. If you want the absolute best performance (it's going to cost you, and you may not notice the difference!), go for Intel's fastest. I personally prefer the AMD Athlon XP and Athlon 64 CPUs.
• My current picks for best AMD CPUs are:
Athlon 64 FX 53 2.4 GHz 400 FSB - personally, I'd never buy this while it is the fastest CPU - it's just too pricey. But, if you must have the best performance, get this! If you need this kind of speed, try to just wait a little while until AMD introduces a faster CPU and this one drops in price. Note, the FX CPUs require socket 940 motherboards which are pricey and a little hard to come by. Those motherboards also require more expensive *Registered* DDR 400 memory.
Athlon 64 2800 1.8 GHz 400 FSB - more expensive than any of hte Athlon XP CPUs, but still a good idea if you want to have future 64-bit compatibility... These Athlon 64 CPUs work in Socket 754 motherboards.
Athlon XP 3000+ 2.1 GHz 400 FSB - A great mid-range performance CPU at a very reasonable price. The Athlon XP CPUs work in Socket A (462) motherboards.
Athlon XP 2500+ 1.83 GHz 333 FSB (Barton core) - Far from the fastest, but a great buy. Better yet, get the Mobile version of this CPU. The mobile version is essentially the same, but it runs at 1.88 GHz, much lower voltage, and is unlocked. All these combine to make this one of the best overclocking CPUs in a long time. Almost everyone can run this CPU at 2.2 GHz, and many get it as high as 2.6 GHz without a problem.

My picks for best Intel CPUs are:
3.4 GHz Pentium IV Extreme Edition - 800 FSB - This CPU has an enormous 2 MB cache, but the cost is also enormous (more than twice the cost of the regular 3.4 GHz at the time of this writing). It's not worth it, but if you must have the speed... :) You could save some money by getting the 3.2 GHz version of either CPU.
3.0 GHz Pentium IV Prescott - 800 FSB - This will perform very well, but it is high priced. It will provide you with good performance though!
2.8 GHz Pentium IV Prescott - 800 FSB - This is only a modestly fast CPU, but still priced fairly high. Unfortunately, that's the way it goes with Intel CPUs. If you're on a tight budget, stick with AMD.
2.4 GHz Pentium IV Prescott - 533 FSB is reasonably priced, but also no performance king...