The MI300X 192GB has about 689% more memory bandwidth (5,300 vs 672 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 689% faster on the MI300X 192GB. The MI300X 192GB fits more of the catalog at Q4/8K — 50 vs 18 of 61 models (192 vs 12 GB VRAM). Largest model that fits the MI300X 192GB but not the RTX 5070 12GB: Qwen3-235B-A22B (235.1B). MSRP is $15,000 for the MI300X 192GB vs $549 for the RTX 5070 12GB. 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 (40 shared models), the MI300X 192GB posts the higher tok/s in 40 rows vs 0. Methodology.