GeForce RTX 4090 vs Radeon RX 7900 XTX
A side-by-side readout for vram.
Understanding vram
VRAM is fast on-card memory dedicated to the GPU. Modern AAA games at 4K with ray tracing comfortably exceed 12 GB; with frame generation enabled, 16 GB is the new comfortable floor.
How much you need
- 1080p high settings — 8 GB minimum, 12 GB comfortable.
- 1440p high — 12 GB minimum, 16 GB comfortable.
- 4K with RT — 16 GB minimum, 20 GB+ for headroom.
- AI / LLM inference — as much as you can buy; 24 GB unlocks 30B parameter models in 4-bit.
VRAM types
- GDDR6 — RTX 30, RX 6000/7000.
- GDDR6X — higher bandwidth, hotter; RTX 40/50.
- GDDR7 — RTX 50-series flagships.
- HBM3/HBM3e — pro/datacenter.
Bus width matters as much as capacity — a 12 GB card on a 128-bit bus often performs worse than an 8 GB card on a 256-bit bus.
This matchupIn this spec, GeForce RTX 4090 and Radeon RX 7900 XTX are effectively tied at 24GB — buyers can treat them as equivalent on vram alone.
What is vram?
Video memory on a GPU, used to store textures, framebuffers, geometry, and ray-tracing acceleration structures. Insufficient VRAM causes texture pop-in, stutter, and outright crashes in modern games.
Read the full VRAM explainer →Other specs on this comparison
See the full Graphics Cards category for all products ranked by Mars Score.