– Why does clock speed matter on a CPU, and why do some top-tier CPU’s have lower clock speeds than some from nearly 10 generations ago?

Question

I have a good understanding of what clock speed is, but why does it matter?

For the second question, I was wondering since for example, the new i9-14900K has a base clock speed of 3.2 GHz, whereas my previous desktop CPU, the i7-4790K, had a base clock speed of 4.0 GHz. Why hasn’t this number steadily gone up thought the years?

In: Technology

Answer 1

You order Doordash and your driver drives at 100MPH. Your food gets there really fast. He could go even faster but it would take a lot more fuel (power) to go even a little faster.

This is ok though because you’re the only person ordering food so your food is delivered at full speed.

Eventually, more people start wanting food delivered. More drivers sign up to delivered but there’s a problem: There’s only 1 road for all the drivers to drive on. This severely slows down the delivery of different foods to different people. You could increase the cars speeds and the speed limit but this becomes more expensive and more dangerous (cars/programs could crash).

So, instead of increasing the speed, we increase the size/amount of roads so more people can drive as close to full speed as possible.

This is essentially how threading works on a processor. You can also add more driver hubs (cores) so your delivery can come from the closest and least congested route possible.

Answer 2

Let me take a crack at it like you were actually 5:

It’s like a race car vs a pickup truck. Race cars are really fast, but they can’t carry very much. The job of the processor is to carry as much as it can, as fast as it can. Processor companies are trying to balance how much they can carry, how fast they can carry it, and their gas mileage (power usage). It’s a lot harder to make the car go faster (think wind resistance increasing exponentially), so they’ve started making it bigger while maintaining the same speed. Some of their pickups can carry a lot more but go a little slower (adding cores while reducing speed). Different models depending on whether you want to go faster or carry more.

Part of why clock speed hasn’t gone up is because of quantum tunneling. The pickups (electrons) are going so fast that sometimes they break the limits of physical reality and start to magically appear in other lanes of traffic, sometimes into oncoming traffic. You can imagine the problems that creates. They don’t know how to fix it yet so they’re just working with what they can.