HBM

What is HBM?

HBM — high bandwidth memory — is a kind of RAM that stacks memory chips vertically, like a tower, and connects them to the processor with an ultra-wide path. Regular RAM spreads chips flat on the board; HBM piles them up right next to the chip so data can rush in and out at extreme speed. It exists to feed power-hungry AI chips.

Why do AI chips need it so badly?

When you train a large model, fast compute isn't enough. If data trickles in too slowly, the chip just waits around — a classic "memory bandwidth bottleneck." HBM's whole job is to widen that pipe, keep the compute fed, and push training speed up.

How does it differ from regular RAM (DDR)?

Bandwidth
HBM moves data several times — sometimes more than ten times — faster than regular memory.
Placement
HBM sits in the same package, right against the processor, so traces are short and latency low. Regular RAM plugs into the board, far away.
Price
HBM is complex and expensive to make, so it's basically reserved for high-end AI chips.

Why does HBM matter?

NVIDIA's high-end GPUs and AMD's accelerators lean on HBM for their throughput. It's become one of the tightest links in the AI supply chain — some say the AI bottleneck today is half chips and half memory.

Bottom line: HBM stacks memory into a tower and parks it next to the chip, feeding AI compute through an ultra-wide pipe.