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Comment by nomel | Hacker News Reader

Could you expand on that?

Why does GHz matter? Performance should be measured as a black box, with the metric being the time it takes to accomplishing some task.

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CPUs in a mobile form factor are thermally constrained. Consider that the 13900 will have a heat sink and dedicated fan. If Apple made a laptop version, they’d be using essentially the same chip at a higher clock frequency. If Apple put it into a Mac Pro, they’d run it higher frequency yet still.

of course there’s more than just thermals. The CPU has to actually be designed to run at a high clock.

I could be wrong but my understanding is that all their CPUs share a good amount of commonality and the major differences are more around packaging (IO connectors etc)

You just look at final performance metrics, ghz/mhz matter back in the 90s. Now you can’t just say higher freq means better because architecture all different

The catch is that we can expect better performance when they increase the clock to be closer to the i9. However, it’s never clear how high it go safely.

You can't just turn up clockspeed and expect linear increase in performance. The chips are packed so dense with transistors that the chips have to do some magic to be able to operate at those clock speeds without frying. Desktop parts don't really care about energy efficiency and are thus designed to be able to operate like that since max performance is more important than efficiency. Microarchitectural design decision allow engineers to pick tradeoffs for where they want to place their chips in the market, but most major advantages between chips come from fabrication. And these days there aren't much gains left to be made there.

CPUs are designed with a certain clock speed in mind. The target frequency affects the design of literally every component. Turn up the frequency too high and signals won't arrive in time. Increasing the frequency to match performance with AMD and Intel might require an almost complete redesign.

Maybe it can run faster given better cooling and less aggressive power-saving. But I'd be surprised if it can be made to clock much higher, else Apple would have done it already. Mobile CPUs already have peak performance well above what they can sustain. An even faster turbo would be used more rarely but would still be useful.

I mean, they won’t just take the same chip, but they can definitely reuse many of its parts and it is not unreasonable to think that they can raise the frequency quite a bit.

Clock speed correlates pretty closely to power consumption within a given family.

It correlates less directly between families, smaller process nodes tend to allow for high frequencies at the same power consumption.

I think OP meant clock speeds don’t matter, relative performance does.

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