1 bit / 400 picoseconds is 2.5Gbit/s, or 10x slower than a 1-bit GDDR7 bus (which the 5090 runs at 28Gbit/s * 512 bits).
To be fair this is non-volatile memory though, so the closest real comparison might be Intel Optame. The speeds actually seem somewhat comparable to DDR5, though even that is starting to run in to physical distance and timing issues. The real questions will be around density, cost, and reliability.
1 bit / 400 picoseconds is 2.5Gbit/s, or 10x slower than a 1-bit GDDR7 bus (which the 5090 runs at 28Gbit/s * 512 bits).
To be fair this is non-volatile memory though, so the closest real comparison might be Intel Optame. The speeds actually seem somewhat comparable to DDR5, though even that is starting to run in to physical distance and timing issues. The real questions will be around density, cost, and reliability.