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For $3000 I would expect a different SoC that has a second integrated memory controller with DDR5 support, even if it leads to an asymmetric memory configuratio
by arcticbull 3y ago
For $3000 I would expect a different SoC that has a second integrated memory controller with DDR5 support, even if it leads to an asymmetric memory configuration.
- brucethemoose2 3y agoThis is easy to say, but tape out costs for a reticle size slab of silicon on an interposer are ~10 figures, at least. It makes zero economic sense for a low volume product like the Mac Pro, even with Apple margins. EDIT: Also, they would have to seriously compromise performance. A number of GPU cores would have to be removed to make room for the bigger memory controller. The bus would have to be even wider with regular DDR5 DIMMs, and it would suck much more power.
- avidphantasm 3y agoThe Studio should have upgradable RAM too IMHO, so they could use such a chip for that too, which would amortize the costs.
- brucethemoose2 3y agoThere is no space for ~16 DIMMs.
- avidphantasm 3y agoMake it taller by one Mac Mini height, no one would care. Also CXL memory modules don’t necessarily have to be the same dimensions of a DIMM.
- brucethemoose2 3y agoThe M2 series does not support CXL, as far as I know. They would presumably use UDIMMs anyway, so maybe there is theoretically space? Still, that would be one heck of a socket/motherboard. I can't imagine how many motherboard layers and socket pins they would need for 16+ channel DDR5 in such a tiny space... If its even possible to manufacture, it would be hilariously expensive.
- arcticbull 3y agoIs that true even with a chiplet or north bridge approach? I feel like we’ve seen plenty of examples of CPUs laid out this way. Yeah with a performance penalty but that 192GB of L4 with direct GPU access would go a long way to making that better.
- brucethemoose2 3y agoApple could indeed fab a small memory controller chip, but I am not sure the M2 Ultra die has the interconnect to support such a thing? AMD makes this looks "easy," but it is not easy, and they built for Infinity Fabric from the start. As said below, the answer is CXL. Apple would be stupid not to support CXL devices on the M3 or M4, though I would not be surprised if they skip it
- arcticbull 3y agoI actually wasn't familiar with CXL, I'll check it out. Thanks!