HBM

HBM, short for High Bandwidth Memory, is memory built by stacking many thin layers of DRAM on top of each other and placing the stack right beside the processor. The point is speed of delivery: a modern AI accelerator can do arithmetic far faster than ordinary memory can hand it numbers, so the memory becomes the bottleneck. HBM widens that pipe dramatically.

The catch is physical. Producing HBM eats roughly three times the silicon wafer capacity per gigabyte compared with ordinary DDR5, so every wafer switched to HBM removes several times as much consumer memory from the market. That single trade-off is the main reason RAM prices have exploded since 2025.