Side-by-Side Comparison
Graphics Cards
GDDR6X vs. HBM3
Comparing 2 standards across 7 specifications. 7 key differences identified.
Comparing:
GDDR6X
HBM3
GDDR6X is not a JEDEC standard -- it's a proprietary memory technology Micron developed specifically in collaboration with Nvidia, first shipping in 2020 with the RTX 3080 and RTX 3090. It uses PAM4 signaling, the same two-bit-per-symbol approach PCIe 6.0 later adopted, to reach 19-21 Gbit/s per pin.
HBM3, announced by JEDEC in January 2022, doubled channel count to 16 within the same 1024-bit bus width and reaches roughly 819 GB/s of bandwidth per stack. It's used predominantly in AI and datacenter accelerators like Nvidia's H100, rather than consumer graphics cards.
Specification Comparison Table
7 Parameters| Parameter / Spec | ||
|---|---|---|
|
Max Bandwidth / Data Rate
|
19–21 Gbit/s per pin | ~819 GB/s per stack |
|
Standard
|
Proprietary (Micron, developed with Nvidia) -- not JEDEC | — |
|
Signaling
|
PAM4 (2 bits per symbol, vs. GDDR5/6's 1-bit NRZ) | — |
|
Introduced
|
2020 (Nvidia RTX 3080 and RTX 3090) | — |
|
JEDEC Standard
|
— | January 2022 |
|
Channels
|
— | 16 x 64-bit (1024-bit total bus, same as HBM2) |
|
Primary Use
|
— | AI/datacenter accelerators |