The MI300X 192GB has about 562% more memory bandwidth (5,300 vs 800 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 562% faster on the MI300X 192GB. The MI300X 192GB fits more of the catalog at Q4/8K — 50 vs 32 of 61 models (192 vs 20 GB VRAM). Largest model that fits the MI300X 192GB but not the RX 7900 XT 20GB: Qwen3-235B-A22B (235.1B). MSRP is $15,000 for the MI300X 192GB 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. Not retail-shoppable: MI300X 192GB (datacenter-class; cloud rental is the realistic way to use it). In the Q4/8K head-to-head below (46 shared models), the MI300X 192GB posts the higher tok/s in 46 rows vs 0. Methodology.