Hello, everyone! I’ve been doing some research into computer hardware lately, and one thing that I keep coming across is this idea that the speed of a processor, while important, isn’t the only thing that affects a computer’s overall performance. I’m having a bit of a hard time wrapping my head around this because I always thought that a faster processor meant a faster computer. Can anyone explain why this isn’t necessarily the case? I’m really interested to learn more about this!
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Hz means a processor can do **something** a number of times per second. GHz means it can do **something** billions of times per second which is amazing but we still don’t know what it’s accomplishing unless you look closer.
A typical operation might be “look up this number from memory and do some math with it” and you can imagine the speed of the memory is very important there. Also if you need to, for example, multiply 2 numbers together, an operation like that requires multiple steps to move the data to the correct part of the CPU and actually do the multiplication operation, which uses more than 1 cycle (Hz) to accomplish. Some CPUs may do it more efficiently than others. If you can finish multiplication in only 4 steps instead of 5 steps but your multiplier design takes up more space on your chip and limits the attention you can pay to other parts of your design like the speed that you can do addition… what do you prioritize?
Modern processors also use tricks to guess what they’re going to do next so they can get a head start on it. This can be extremely useful but also complicated, works differently depending on the exact task, and of course if it is done wrong it’s a lot of wasted effort. The Pentium 4 processor is an infamous example of a processor that did this differently from other designs and did a very bad job *in certain tasks* because its predictive execution (guessing the next step) was frequently wrong.
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