> they
destroy x86 lineage chips on performance per watt.
This isn't really true. On the same process node the difference is negligible. It's just that Intel's process in particular has efficiency problems and Apple buys out the early capacity for TSMC's new process nodes. Then when you compare e.g. the first chips to use 3nm to existing chips which are still using 4 or 5nm, the newer process has somewhat better efficiency. But even then the difference isn't very large.
And the processors made on the same node often make for inconvenient comparisons, e.g. the M4 uses TSMC N3E but the only x86 processor currently using that is Epyc. And then you're obviously not comparing like with like, but as a ballpark estimate, the M4 Pro has a TDP of ~3.2W/core whereas Epyc 9845 is ~2.4W/core. The M4 can mitigate this by having somewhat better performance per core but this is nothing like an unambiguous victory for Apple; it's basically a tie.
> I have an M1 Max, a few revisions old, and the only thing I can do to spin up the fans is run local LLMs or play Minecraft with the kids on a giant ultra wide monitor at full frame rate. Giant Rust builds and similar will barely turn on the fan. Normal stuff like browsing and using apps doesn’t even get it warm.
One of the reasons for this is that Apple has always been willing to run components right up to their temperature spec before turning on the fan. And then even though that's technically in spec, it's right on the line, which is bad for longevity.
In consumer devices it usually doesn't matter because most people rarely put any real load on their machines anyway, but it's something to be aware of if you actually intend to, e.g. there used to be a Mac Mini Server product and then people would put significant load on them and then they would eat the internal hard drives because the fan controller was tuned for acoustics over operating temperature.