I created it. I have the original .odg file. You're wrong.
I created the above .odg diagram with RDNA's 64-bit memory controllers attached to duel-linked GDDR6 chips
Four 16bit memory channels are attached to one RDNA's 64 bit memory channel.
Look it'd be neat if they did something like this to work around that possible quirk, but the problem is we've seen the chips on the XSX motherboard and they're arranged three to one side, three to the other side, and four along the top. The graph here doesn't match up with the actual PCB's chip layout, and we can assume the four chips along the top are the 1 GB modules.
I'm not completely dismissing your general idea, but it wouldn't be using what's suggested in that graph because the module layout on the graph doesn't match the actual module layout on the real motherboard.
I'm saying neither are SSG because SSG is for PC-based workstations... but the basic concept of extending the VRAM through SSD, both next-gen system are doing this; and due to the customizations and speed, PS5's solution seems a lot better than Xbox's.
I've read that MS were originally intending to include a normal HDD in XSX and then they went to a 1.4 - 1.8 GB/s SSD, before finally deciding to settle on what they have now based on catching wind of how much attention Sony was putting into their SSD.
Basically, having followed the rumors and progression of leaks of XSX, the image forms of XSX's SSD not being as integral to the design of their system as PS5.
As a rumor, that sounds....iffy. It's kind of in the same ballpark as the rumors Sony upped the PS5 GPU clock in panic to close some of the TF delta with XSX.
I doubt either of those rumors are actually true. Also while I expect PS5 to have the SSD advantage regardless of what additional we find out, we don't have all the details on XSX's setup yet. Just a couple days ago they just iterated on the expansion card having the same performance as the internal drive. It might be possible they've designed a setup where if the user has an expansion card, the OS can leverage it for dynamic performance gains in terms of data caching and streaming with the internal and external drives in tandem (it's just that games wouldn't be able to program against the internal/external setup since not everyone is guaranteed to have one...or maybe they can, if it ends up being little costs in labor and time to do).
There's other parts to it as well that we don't really know a lot on that could bring the SSD performance between the two closer to spec parity at least in some ways, but that's just me keeping the door open in expectations with that.
Yes but 448GB/s was likely not enough to feed the XSX GPU in their tests so they went with this setup
Also something interesting ree users mentioned how both Sony & MS came about to the same amount of GB/s per TF, was likely a performance sweet spot where extra bandwidth didn't justify costs
True; I was focusing more on the physical memory amounts there, though. 560 GB/s gives a bandwidth advantage but only on 10 GB of physical memory, and of course there's still the contention issues between GPU, CPU etc. Basically the PS5 doesn't really have to "choose" memory amounts in its case.
Say PS5 uses 2 GB for the OS, and the CPU wants to use 3 GB of physical memory for something. That's 11 GB to GPU. XSX has 2.5 GB for OS (in the slower pool, MOTL), and same scenario, CPU wants 3 GB of physical memory for a task. 10.5 GB for the GPU, but 500 MB of that will have to sit in the "slower" pool. Or, the dev can put that CPU data in the 10 GB pool but now that leaves GPU with just 7 GB of data to work on.
I wanted to bring the OS back up because one thing we already know is that the OS sits in the slower pool (2nd 1 GB partition of 2x 2 GB modules) of memory. Already, if the system needs to do any OS calls, it has to switch to the slower pool anyway because that's where the OS data is at. That's part of the reason I've been speculating that there are probably design elements in place to allow for rapid cycle access between the fast and slow pools. There should also be ways for games to shuffle data between the fast and slow memory pools as needed, minus 2.5 GB for the OS.
Those will have to be ways for devs to maximize the physical memory amounts, a bit more work than what they have to do on PS5 since the bandwidth and memory setup are more straightforward there. But it will be interesting to see when games finally do that.