HBM4 vs HBM3E: what doubles, and why it matters
- HBM4 doubles I/O pins from 1,024 to 2,048 and channels from 16 to 32, taking per-stack bandwidth past 2TB/s
- The base die moves from a memory process to a foundry logic process, improving power efficiency by more than 40%
- Unit cost rises, but accelerator throughput gains more, because memory bandwidth binds before compute does