HBM · High-Bandwidth Memory
Stacked DRAM mounted on-package with the accelerator; the bandwidth and capacity ceiling and the key supply bottleneck.
Vertically stacked DRAM bonded next to a processor for huge memory bandwidth; AI's binding supply constraint.
Also written as: High-Bandwidth Memory · HBM3
Current numbers
~8 → 19.2 TB/sPer-GPU HBM bandwidth, HBM3E (B200/B300) to HBM4 (shipping Vera Rubin, 8 stacks): ~2.4x
80 → 288 GBPer-GPU HBM on shipping parts: H100 80 GB, HGX B200 180 GB, B300 288 GB, Vera Rubin 288 GB
vast majority contractedMicron agreements cover the vast majority of its calendar-2027 HBM bit supply (September 30, 2026)