High Bandwidth Memory (HBM) addresses the memory bottleneck in AI accelerators by utilizing a vertical stacking architecture rather than the traditional 2D layout used in consumer GPUs. While standard GDDR memory is limited by the physical space available on a circuit board, HBM stacks DRAM dies directly beside the processor. This vertical approach, known as 2.5D packaging, uses a silicon interposer to facilitate high-density connections between the memory stack and the processor. To enable communication between these stacked layers, engineers use through-silicon vias (TSVs), which act as vertical data channels, and micro-bumps that bond the layers together. This design allows for significantly higher memory bandwidth, exceeding 1.2 terabytes per second in current HBM3E implementations, which is essential for preventing compute cores from idling during complex AI model execution. Despite these performance advantages, HBM is not currently viable for consumer gaming hardware due to the high manufacturing costs associated with precise alignment, complex thermal management, and the need for custom-designed chip packaging.
HBM addresses memory bandwidth bottlenecks by stacking DRAM dies vertically beside the processor. The 2.5D packaging method uses a silicon interposer to connect memory stacks to the processor.
Through-silicon vias and microscopic solder bumps are required to facilitate communication between stacked memory layers. HBM3E technology currently enables memory bandwidth speeds exceeding 1.2 terabytes per second.
Consumer gaming GPUs continue to use GDDR memory because it offers a better balance of cost and manufacturability. Manufacturing HBM requires precise alignment and thermal management, which increases the overall production cost.
Chapter guide
Worth noting
- The video is sponsored by Micron Technology, a manufacturer of HBM products.
- The discussion of future HBM4 and HBM4E specifications is based on industry roadmaps rather than currently available hardware.