The craziest thing is how close they get at 3W. That's the part that's staggering. What could Apple do with, say, laptop thermals? Desktop thermals? The mind creeps closer to boggling.

It's not that staggering. Use the above example. It's comparable to one thread of the 56 thread Xeon 8176.

That server CPU has a TDP of 165W. That's 2.95W per thread. So pretty much entirely on par with Apple.

Well, except that hyperthreads are not the same as cores, so it's not quite equivalent. My understanding is that the two hyperthreads for a core share some execution resources, but are able to run in parallel for other resources. That means some workloads won't benefit much at all, others will benefit greatly, and the usual case is somewhere in-between.

Also, I think I've heard people here noting how hyperthreading causes some workloads to go slower (possibly from CPU heat throttling? Dunno) so some people disable it in the BIOS first thing.

So the truth is likely somewhere between 2.95W/thread and 5.90W/core (assuming 165W is even correct, there's comments here noting while AMD and ARM quote max, Intel quotes operating average...).

But that’s not a useful comparison, because you can’t run a Xeon at 2.95W. There is a floor wattage that the processor simply cannot go below.

User interface drawing/responsiveness depends most on single core performance.

IIRC one of the changes from the A10 to the A11 was that the different sized cores started being able to run simultaneously.

Apparently the smaller Tempest core from the A12 is being used as the main core in the new Apple Watch. Talk about, uh, synergy.

Yeah. The S4 Apple watch SoC is actually using Two Tempest (LITTLE) cores.

Pretty awesome, if you think about It. That little watch is more powerful than it appears.