Memory manufacturer SK hynix is developing HBM3 memory that offers a bandwidth of more than 665GB/s per chip. That is a significant improvement over HBM2E, which has a bandwidth of up to 460GB/s.
In addition to the bandwidth of more than 665GB/s, HMB3 enables an I/O speed of more than 5.2Gbit/s, SK hynix reports on a page about HBM2E. The speed of HBM2E is 3.6 Gbit/s. The Korean memory manufacturer does not say when HBM3 is due to appear, only that it is currently in development.
The numbers are about bandwidth per chip and as Tom’s Hardware notes, GPUs and FPGAs can currently have about four to six memory stacks based on HBM2E, for a bandwidth of 1.84 to 2.76TB/s. With HBM3, that would increase to 2.66 to 3.99TB/s with comparable stacks.
Standardization organization Jedec has not yet announced anything about HBM3. At the end of 2018, that organization issued an update to the HBM2 specification, which manufacturers have come to call HBM2E. Micron hinted last year that he was working on HBMnext, which could indicate HBM3. That should appear at the end of 2022.