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.
For those, like me, who wondered how much data was written in 400 picoseconds, the answer is a single bit.
If I’m doing the math correctly, that’s write speeds in the 10s-100s GBps range.
If it’s sustainable.
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.
You can always parallelize, this would be more beneficial for latency.