The speed of CPUs

The CPU is the brains of the computer and it has recently become a lot more complicated to figure out what you are getting as far as performance. It used to be that processors had simple names and there were a few choices. Now there are hundreds of processors with names like Intel Pentium Dual-Core E2220, or AMD Phenom X4 9950.

It used to be that a Windows computer with 3 Ghz processor was faster than a 2.5 Ghz processor. This is no longer the case. You have to look at all the variables and figure out the funny names mean.

Very few single core processors are still being made. Almost all computers come with at least dual processors because of the nosedive in price. This means that one core of the processor can handle your background tasks, and the other core can handle your active task with no performance slow down (unlike a single core). Apps need to be muliply threaded to take full advantage of quad processing.

Another big consideration is the processor’s L2 cache. This caches recent memory data from the disk into memory so that the data will be instantly available to the processor without hitting the disk. Intel uses one cache for all cores, while AMD gives a cache to each processor. The bigger the cache (in megabytes), the better the performance, because the computer will not have to do as much disc access.

Furthermore, there is the front-side bus (FSB) speed, which determines how fast the CPU can transfer memory bits to the motherboard memory controller. The motherboard must be capable of receiving all the bits that the CPU is sending it, or there will be a performance bottleneck. AMD processors don’t have a FSB however. They transport the memory on the HyperTransport bus link!

You can also increase computer speed just by changing some muliplier settings in the bios – for free. But you do this at your own risk. Your computer might blow up. It is called overclocking, and you should only do it if you know what you are doing!

The cost of processors continue to shoot downward.

How much do you think you can get a 2.4 GHz Pentium Dual-Core E2220, with 1 MB L2 cache, and an 800 Mhz FSB speed?

a. $84

b. $200

c. $400

d. $1000

The correct answer is ‘a’. It only costs $84.

So in 2008, a 3Ghz processor could be faster than a 4Ghz processor.

So how can you figure out how fast your processor is? One way is to download Passmark’s PerformanceTest 6.1, which is free for 30 days and is available here – http://www.passmark.com/ and run all tests. I got a 415 on all tests for my computer at work, and a 265 for all tests on my laptop at home.

Main reference for this post: Computer Shopper, Sept 2008 – Processor Oriented by Matthew Murray, p. 57-61

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