What makes one CPU faster than another CPU?
In: Technology
Other than the speed of the clock ticking (the GHz number), two main differences are how much it can do concurrently (in parallel), and how much ultra-fast “cache” memory it has.
Both of these require more transistors, which drive up the cost of manufacture.
There’s a difference between “faster” and “more powerful”. I’ll address “faster”.
The key thing in being faster is of course the clock speed. The internal clock of a microprocessor synchronizes most of the processing within the chip, kind of like marchers moving along to the beat of a drum. Faster beat, faster marching.
But there’s at least one other aspect of “faster”, which borders on “more powerful”. That is how many clock ticks it takes to do a given operation. If processor A is clocked at 2 GHz and takes 4 clock cycles to execute a floating point multiply, and processor B is clocked at 1 GHz and takes 1 clock cycle to do a FP multiply, processor B is faster (at doing that particular thing) even though A is clocked at a higher rate of speed.
A processor is just a machine. If we have a paperclip making machine, that machine takes wire in on one side, and spits paperclips out the other side. How can we make the machine make paperclips faster? One way is to literally speed up the machine. Take the motor that drives the machine and make it go faster. Make the motor twice as fast, you make twice as many paperclips.
Processors work the same way. However, instead of taking wire in and spitting paperclips out, a processor takes numbers in and spits other numbers out. The processor might take the numbers 8 and 9 in on one side, and spit out what you get when you add those numbers, 17. Just like the paperclip machine has a motor, the processor has something called a “clock signal”. The clock signal controls how fast the processor does stuff. Make the clock signal faster, and the processor will run faster. If you’ve ever heard of the term “overclocking”, that’s all it is.
So, why don’t we run all processors infinitely fast? For the same reason we can’t run the paperclip machine infinitely fast. The paperclip would probably jam up and break if we ran it too fast. With a processor, we might start getting the wrong answers out of it.
Processors can also be made to have more “cores”. Imagine if we designed our paperclip machine to make two paperclips at once. We can run it at the same speed, and get twice as many paperclips out of it. We can do the same thing with processors. Make it so it can do two different additions at the same time, and we can kind of get twice as much work done with a processor that runs at the same speed.
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