HBM vs Standard DRAM Bandwidth

Memory Bandwidth: HBM vs Standard DRAM

Why the AI inference bottleneck is a memory problem, not a compute problem

Peak Bandwidth (GB/s per module)

DDR5

~80

Standard laptop / desktop — baseline reference

LPDDR5X

~120

Mobile / edge AI devices

HBM3

~1,200 GB/s

H100 GPU — current data center standard

HBM4

~2,000+ GB/s

Next-gen AI accelerators — SK hynix / Samsung target

Stack Architecture Comparison

DDR5 / LPDDR5

Single die, flat layout. Data moves laterally across a PCB bus. Long signal path = latency. Bus width: 64–128 bits.

HBM3 / HBM4

8–16 DRAM dies stacked vertically. Through-Silicon Vias (TSVs) connect each layer. Bus width: 1,024 bits. Placed directly on interposer beside logic die.

16×

HBM4 bandwidth advantage over DDR5 at comparable power envelope

<50%

GPU utilization when memory bandwidth is the bottleneck — wasted compute spend

5–8

HBM3 stacks per H100 accelerator card — demand scales with AI cluster size

Source: IEEE Solid-State Circuits Journal; SEMI HBM Technology Roadmap 2026; SK hynix HBM4 product brief (preliminary specifications).