The H100 80GB SXM5 has about 635% more memory bandwidth (3,350 vs 456 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 635% faster on the H100 80GB SXM5. The H100 80GB SXM5 fits more of the catalog at Q4/8K — 46 vs 18 of 61 models (80 vs 12 GB VRAM). Largest model that fits the H100 80GB SXM5 but not the Arc B580 12GB: gpt-oss-120b (120.4B). MSRP is $249 for the Arc B580 12GB vs $30,000 for the H100 80GB SXM5. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price. Not retail-shoppable: H100 80GB SXM5 (datacenter-class; cloud rental is the realistic way to use it). In the Q4/8K head-to-head below (40 shared models), the H100 80GB SXM5 posts the higher tok/s in 40 rows vs 0. Methodology.