High Bandwidth Memory (HBM)

High Bandwidth Memory sits right beside the GPU, ferrying data at high speed. Ordinary memory chips are laid out flat on a board next to the processor, but HBM stacks multiple memory chips on top of each other like floors in an apartment building, then connects them to the GPU over the shortest possible distance. By stacking layers and shrinking the distance, the amount of data that can move at once increases dramatically.

Think of regular memory as a sprawling network of narrow roads, while HBM is like a high-speed logistics terminal built right next to the destination. When training or running an AI model, the GPU constantly has to read and write huge piles of numbers. If that logistics is slow, the whole job hits a bottleneck no matter how fast the GPU itself can crunch numbers. That's why virtually every modern AI accelerator ships with HBM built in.

However, HBM is complicated to manufacture and production capacity is limited, so when demand for AI servers surges, it's often the component that runs short even before the GPUs themselves do.