[mapt]

For PC CPUs, there are already so many watts per square millimeter that many of the top tiers of the recent generations are running thermally throttled 24/7; More cooling improves performance rather than temperatures because it allows more of the cores to run at 'full' speed or at 'boost' speed. This kills their profitable market segmentation.

In this environment it makes some sense to use more efficient RISC cores, and to spread out cores a bit with dedicated bits that either aren't going to get used all the time, or that are going to be used at lower power draws, and combining cores with better on-die memory availability (extreme L2/L3 caches) and other features. Apple even has some silicon in the power section left as empty space for thermal reasons.

Emily (formerly Anthony) on LTT had a piece on the Apple CPUs that pointed out some of the inherent advantages of the big-chip ARM SOC versus the x86 motherboard-daughterboard arrangement as we start to hit Moore's Wall. https://www.youtube.com/watch?v=LFQ3LkVF5sM