GDDR

GDDR, or graphics double data rate memory, is DRAM designed for bandwidth rather than capacity. It sits soldered on the graphics card next to the GPU die, not in the DIMM slots standard DDR memory uses. Higher clock rates across a wider bus move large blocks of data for rendering and parallel compute workloads.

Standard DDR5 runs around 5,600 to 8,000 MT/s across a 64-bit channel per DIMM. GDDR6 runs 14 to 20 Gbps per pin across a 32-bit interface per chip, and GDDR7 pushes past 28 Gbps per pin. An RTX 4090 pairs 24 GB of GDDR6X with a 384-bit bus for roughly 1,008 GB/s of bandwidth, against the 80 to 100 GB/s a dual-channel DDR5 desktop delivers.

GDDR capacity is fixed at the factory, not upgradable the way DIMM based system memory is. VRAM size at purchase is a hard ceiling for the life of the card.

Sources

Last verified August 29, 2026.