Hardware Computer

How to Choose a Microprocessor/CPU?
By Dr. Michael & Lee Penrod

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* Choices: In the current market you have seven main categories of microprocessors to choose for your desktop computers: Xeon, Pentium IV, Pentium III, Celeron, Opteron, Athlon, and Duron.

* Pentium 4 Socket 423 vs Pentum 4 Socket 478: Recently Intel released two versions of the Pentium 4: Socket 423 and Socket 478. Socket 423 was short lived and didn't go past 2.0GHz. At this point there is very little support for it. We recommend going with Socket 478 for all new Pentium 4 based systems. We have a detailed guide covering this topic.

* Pentium 4 Socket 478 vs Celeron Socket 478: Performance wise the Pentium 4 is up to 25-30% faster compared to an equal speeded Celeron. Celeron Socket 478 is best used where budgets are extremely tight but Intel is a requirement.

* Pentium 4 Socket 478 vs AMD Athlon XP Socket A You give a little, you take a little. Overall the performance of Athlon XP processors is very high. Archetectually these processors are very different and as such they can not be compared fairly when looking only at speed in MHz or GHz. To make true comparisons performance testing must be used. AMD realized this and uses a performance based model numbering system. When looking at the model number performance can be roughly equated to GHz speed +/- 100MHz. For example a AMD Athlon XP1700+ processor is going to compare favorably to a Pentium 4 1.7GHz processor. On some tasks the AMD part will be faster, on others the Intel will be faster. For most people the AMD part is a better deal because it can run everything the Intel part can and is often much cheaper.

* Bus Speeds / Front Side Bus The bus speed is a very important aspect of your processor choice. Generally: The higher the better when you are talking about like processors. Front Side Bus speed affects your performance level. For more information on this topic please see our FSB Guide.

* Pentium IV vs Pentium III: While the Pentium IV boasts a high clock rate, the clock rate isn't directly comparable to that of previous processors due to design changes. (While a P4 1.4ghz may be 400mhz faster then a PIII 1GHz, but the P4 may fall behind the PIII in some tasks). As time progresses, software developers are optimizing their programs to better take advantage of the new features of the P4. At this point the Pentium III is starting to dissappear though, we recommend going with the newer Pentium 4 Socket 478.

* Pentium III vs. Celeron: Besides the obvious price differences, the main technical difference between Pentium III and Celeron is that Pentium III has 512k level 2 cache while Celeron has only 128k. This difference is however very misleading. Cache is used to speed up the CPU access to repeatedly used data in memory and it is very critical for activities such as gaming and 3D computing. If all you plan to use your computer for are word processing, e-mail and surfing the web, Celeron is a very economic choice. That’s often the case for most office applications. However, if you want to use your computer for games and high-end computing, Pentium III with more cache would be a better choice. This sounds just the opposite of what Intel has been trying to market their products.

* AMD now vs. AMD's past: AMD microprocessors have gained popularity in the last couple of years, mainly as a result of the success of Athlon. Their price, speed, and 3D performance are very attractive for people who don’t care about the name of a product but the contents. Historically, AMD gained their first converts among technically oriented people who like to venture into something new and different. The business world is taking a longer time to accept them, partially due to inertia and image problems. AMD is now leading in the top-speed performance for PC and has won many benchmarking tests.

* Athlon vs. Duron: From AMD - The AMD Duron processor is a derivative of the state-of-the-art AMD Athlon processor. Although the two processors are related, there are key differences in the CPUs and the platforms designed to support them, reflecting the requirements of their target markets. Specifically, the AMD Athlon processor is planned to be available at higher clock rates, and features more full-speed, on-chip cache memory. The AMD Duron processor was designed to consume less power than the AMD Athlon processor, thereby enabling lower cost systems. Additionally, AMD Duron processor-based PCs are likely to employ lower cost memory and graphics solutions. When comparing equal speed Celeron processors to Duron processors the Duron is almost always faster.

* Athlon vs. Thunderbird: Thunderbird is the AMD internal code name for the new AMD Athlon processor with performance enhancing cache memory. The new AMD Athlon processor now features performance enhancing cache memory. Putting the 256KB L2 cache on chip enhances the performance of the AMD Athlon processor. Additionally, the new AMD Athlon processors are primarily available in sockets (Socket A). In other words, Thunderbird is a nickname for a new type of Athlon.

* Athlon Slot A vs. Athlon Socket A: The classic Slot A Athlon has virtually disappeared from usage, and has largely been replaced by the Socket A Thunderbird & Duron processors. Those building new systems are advised to go with the socket interface vs slot.

* Opteron vs Xeon vs MP: The Opteron is AMD's new 32/64bit processors mainly targeted at servers. It offers many innovative features compared to the Athlon MP (AMDs current generation of server processors). They key ability of the Opteron over other processors is that it is capable of 64-bit processing which isn't possible with the MP or Xeon. The currently generation of Xeon processors is very similar to the Intel P4. All three of these type of processors can be used to make a reliable server system, provided you can locate all the parts you need to make it. Typically server motherboards (dual/quad cpu) are harder to locate then other types of motherboards and are much more expensive.

* Software compatibility problems for AMD processors are very rare. If you are using some very specialized software (often very old, too) designed only with Intel processors, you might run into some problems.

* Heat Considerations: Higher speeds means more heat from the CPU. The microprocessor cooling has become much more important and sophisticated than in the 486 and Pentium ages. Consider using a huge heat sink, efficient CPU fan, front and rear case fans, fan duct, and an efficient case among other tools to keep your processor cool.

* Power Considerations: As the CPU speed increases, the need for a more reliable and powerful power supply increases. Choose the best power supply your budget can afford.

* Reliability: Among all computer components, microprocessors are among those with the least return rates and thus the highest reliability, which is true for all brands of microprocessors. This is probably due to the fact that the microprocessors are mass-produced by machines with little if any, human interaction. In addition, the quality control process can be automated.

* Once you have made a decision on the category of the microprocessor, choose the highest speed your budget can allow in that category. Keep in mind that the overall speed of a computer system depends on: microprocessor speed, size of RAM memory, size of cache, hard drive access speed, and video speed. You often have to pay too much to reach the top performance speed. For instance, the top speed may give you 20% more in performance than the next level down, but the price may be 100% more.

* Price vs. Performance: There is typically no good correlation between these two factors, especially at the top speeds. Average users should not purchase the top-speed on the market. The price difference is not worthy of the performance difference.

* Motherboard Considerations: Different microprocessors may require different motherboards. Choosing a motherboard first may help you choose the processor. If you already have a motherboard, consult your motherboard’s manual to determine which microprocessor to use. If you are shopping for a motherboard then take a look at the specification for it and or the motherboard manufacturer website. They often provide CPU support lists that can be very helpful. In any event: Don't try putting a square peg in a round hole. Make sure that the socket or slot type of the motherboard matches the socket or slot type of the processor.

* Upgrade Considerations: Check the highest speed that your motherboard would allow for that category of processors to see how much higher you could upgrade to without changing the motherboard.

* Over Clocking: See our over clocking guide for details