Apologies in advance if it feels like a re-run on the XsX memory bandwidth discussions - I really don't think it is.
Anyway, it occurred to me that it was stated that XsX IO/decompression is done on a CPU core, so on that premise, if a game is streaming continuously in a REYES situation, how much of the effective 560GB/s peak memory bandwidth is the XsX able to utilise? And how much of it is lost to CPU involvement in IO, as it was vaguely stated IIRC that the CPU use reduces asymmetric access bandwidth down to 336GB/s.
Taking that thought about the IO/decompressor a bit further, when looking at the RAW versus decompression unit limits on the two consoles, the XsX is 2.4GB/s raw and 6GB/s through CPU core VA decompression, which is a max 2.5x benefit.
The PS5 is 5.5GB/s raw and 22GB/s through IO complex decompression , which is a max 4x benefit.
Looking at the PS5, because it has a simple unified memory setup, for it state 22GB/s theoretical figure the IO complex is(IMO) copying at maximum width from the SSD at raw and then through the decompressor, outputting to all 8 of the 32bit GDDR6 modules simultaneously, so we can then say that the 4x is a 256bit width(in the IO complex) and the 1x raw represents 64bit from the SSD controller interfacing with the 64bit Zen2 subsystems.
From the above, it seems like the 12 channel SSD in the PS5 is only internally different, so presumably the XsX SSD is also 1x at 64bit for its 2.4GB/s and (2.5 x 64bit) 160bit at output from CPU decompression through AVX2 or custom SIMD – which interestingly isn’t the 6 x 32bit memory channels (of GDDR6 @14Gbps) giving 336GB/s bandwidth, which was expected above. Instead the 160bits is exactly half the memory width of the 10x 32bit memory channels that gives the GPU 10GB of GDDR6 their 560GB/s bandwidth.
So if what I’ve speculated makes sense, and the XsX decompressor expands compressed data to memory at 160bit width – which seems compatible as it fits inside both the 10GB’s 320bit width and the 6GB’s 192bit width - then a logical question arises: Does the XsX’s asymmetric setup actually have a 3rd bandwidth setting that is 280GB/s - when copying from or to the SSD?