| That diminishing return is much more true at 150w than at 50w. https://www.anandtech.com/show/16214/amd-zen-3-ryzen-deep-di... When you look at per-core performance of desktop chips, things aren't rosy. Looking at the 5950 (most power efficient per core), it's taking almost 7.5w PER CORE to hit 3.7GHz. It hits 4.7GHz (peak frequency of 6850U) on just 4 cores while using 110w to do it. That's almost 23w per core. Based on these numbers, taking 8 cores up to 3.7GHz would require 60w of power and that's just to hit the "base" frequencies of the 6850H which they say can be done with a TDP 25% lower than that (maybe dropping half the L3 cache makes that possible, but at an overall performance loss as moving stuff from RAM takes more energy than keeping it in L3 and I don't know that losing half the cache saves more energy than the addition of a GPU adds back to the chip). Even if we assume a 12% energy efficiency bump (two thirds of the 18% transistor reduction and roughly inline with the 30% efficiency at N5 with a 45% transistor reduction), we aren't doing anything multithreaded anywhere near peak frequency. In fact, we aren't doing anything multithreaded past those terrible 2.7GHz base clocks at best. Meanwhile, the M2 TDP didn't really increase. They can hit 3.5GHz on 4 cores while using 60% less energy than those AMD cores at 3.7GHz despite being about twice as wide and over 60% faster per clock. Back of the envelope calculations seem to indicate that 4 M2 big cores at 3.5GHz should be more than 2x as fast as 8 Zen 3 cores at 2.7GHz without even using little cores and completely ignoring Amdahl's Law. Of course, all this just goes back to the question of how questionable this entire article really is. |
The intel competition in the form of alder lake scales for much longer if you just pump more juice into it. Scaling varies from chip to chip.
Edit - I might be misremembering, because 6900HS's sweet spot was at 20W: https://www.anandtech.com/show/17276/amd-ryzen-9-6900hs-remb... But anyhow, they also noted that "going from 50 W to 80 W is a 60% power increase for only +375 MHz and only +7.7% increased score in the benchmark".
But TL;DR: 15-28W probably really is the ideal range for a chip like this. Which won't stop ODMs from pushing well beyond that, of course.