The RX 7900 XT 20GB has about 85% more memory bandwidth (800 vs 432 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 85% faster on the RX 7900 XT 20GB. The RX 7900 XT 20GB fits more of the catalog at Q4/8K — 32 vs 18 of 61 models (20 vs 12 GB VRAM). Largest model that fits the RX 7900 XT 20GB but not the RX 7700 XT 12GB: GLM-4.7-Flash (31.2B). MSRP is $449 for the RX 7700 XT 12GB vs $899 for the RX 7900 XT 20GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price. In the Q4/8K head-to-head below (40 shared models), the RX 7900 XT 20GB posts the higher tok/s in 33 rows vs 7. Methodology.