Thread: Apple M1 SoC
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Old 2020-11-18, 01:12   #13
M344587487's Avatar
"Composite as Heck"
Oct 2017

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Originally Posted by Ethan (EO) View Post
Whatever they put in the iMac refresh will probably be that first high core-count part.
That didn't sound right until I looked and there is precedent in that the A12X has two more cores than the A12. Then again it looks like the imac has just been refreshed, is it likely they'll refresh so soon?

Originally Posted by Ethan (EO) View Post
Once that works down to the Mac mini these will be very attractive for energy efficient compute with great granularity of cost and space.

But for now, single-threaded performance is faster than any other consumer CPU out there in specint and specfp2006. 10% higher specfp2006 than Ryzen 9 5950x in second place. All 4 big cores can run at full speed at the same time, so anything that fits the cache hierarchy well is going to be pretty zippy, but single core can saturate main memory at ~60GB/s.
Anandtech suggests that the cache is partitioned somehow, the number of compute workloads that fit the M1 hardware well might not be as high as we'd like.

Originally Posted by Ethan (EO) View Post
The power draw figures are at-the-wall, and the Mac Mini may not be totally optimized for platform energy consumption, so I think the efficiency is hard to evaluate at these low wattage levels.
For reference, from memory my 4700u mini-PC idles at ~4.5W and consumes ~20.5W total when the SoC target is 11W. Assuming the target matches reality which I'm inclined to think is true, this indicates that the SODIMM DDR4 consumes ~5W under load. One of the main points of LPDDR4X is that it's energy efficient, I don't think it's unreasonable to guess that the LPDDR4X has an upper bound of ~4W under load if the SODIMM's 5W figure is accurate. With the idle figures in the article that gives ~9W of power not consumed by the SoC when under load so the SoC consumes ~22W for the compute MT workload in the article. That sounds like it'd be quite a bit above the M1's sweet spot which I'm assuming is somewhere in the 5-10W range. If I'm wrong and the sweet spot is say 15W then the figures turn out a bit worse for the M1, as then it's more reasonable to directly compare it to the 4800u.

Originally Posted by Ethan (EO) View Post
Between this and AMD’s roadmap, we have some degree of competition in mass market CPUs for the first time in quite a while!
I hope Apple drags other ARM producers into the performance category, Apple is competition only in a loose sense in that there's no way in hell many people will switch to or from them.
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