Comment by wqaatwt
M4 still has >2x better performance per watt than either of those chips. Of course they are pretty much ignoring desktop so they can’t really compete with AMD/Intel when power is not an issue but that’s not exactly new
M4 still has >2x better performance per watt than either of those chips. Of course they are pretty much ignoring desktop so they can’t really compete with AMD/Intel when power is not an issue but that’s not exactly new
I guess that depends on your definition of “desktop”.
What that really means (I think) is they aren’t using the power and cooling available to them in traditional desktop setups. The iMac and the Studio/Mini and yes, even the Mac Pro, are essentially just laptop designs in different cases.
Yes, they (Studio/Pro) can run an Ultra variant (vs Max being the highest on the laptop lines) but the 2x Ultra chip so far has not materialized. Rumors say Apple has tried it but rather could get efficiencies to where they needed to be or ran into other problems connecting 2 Ultras to make a ???.
The current Mac Pro would be hilarious if it wasn’t so sad, it’s just “Mac Studio with expansion slots”. One would expect/hope that the Mac Pro would take advantage of the space in some way (other than just expansion slots, which most people have no use for aside from GPUs which the os can’t/won’t leverage IIRC).
M4 has ">2x better performance per watt" than either Intel or AMD only in single-threaded applications or applications with only a small number of active threads, where the advantage of M4 is that it can reach the same or a higher speed at a lower clock frequency (i.e. the Apple cores have a higher IPC).
For multithreaded applications, where all available threads are active, the advantage in performance per watt of Apple becomes much lower than "2x" and actually much lower than 1.5x, because it is determined mostly by the superior CMOS manufacturing process used by Apple and the influence of the CPU microarchitecture is small.
While the big Apple cores have a much better IPC than the competition, i.e. they do more work per clock cycle so they can use lower clock frequencies, therefore lower supply voltages, when at most a few cores are active, the performance per die area of such big cores is modest. For a complete chip, the die area is limited, so the best multithreaded performance is obtained with cores that have maximum performance per area, so that more cores can be crammed in a given die area. The cores with maximum performance per area are cores with intermediate IPC, neither too low, nor too high, like ARM Cortex-X4, Intel Skymont or AMD Zen 5 compact. The latter core from AMD has a higher IPC, which would have led to a lower performance per area, but that is compensated by its wider vector execution units. Bigger cores like ARM Cortex-X925 and Intel Lion Cove have very poor performance per area.