Earlier quoted context omitted.
The M3 Max was 400GBps, this is 540GBps. Truly an outstanding case for unified memory. DDR5 doesn't come anywhere near.
It's not "DDR5" on its own, it's a few factors. Bandwidth (GB/s) = (Data Rate (MT/s) * Channel Width (bits) * Number of Channels) / 8 / 1000 (8800 MT/s * 64 bits * 8 channels) / 8 / 1000 = 563.2 GB/s This is still half the speed of a consumer NVidia card, but the large amounts of memory is great, if you don't mind running things more slowly and with fewer libraries.
Was this example intended to describe any particular device? Because I'm not aware of anything that operates at 8800 MT/s, especially not with 64-bit channels.