The RTX 5070 12GB has about 77% more memory bandwidth (672 vs 380 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 77% faster on the RTX 5070 12GB. The RTX 5070 12GB fits more of the catalog at Q4/8K — 18 vs 17 of 61 models (12 vs 10 GB VRAM). Largest model that fits the RTX 5070 12GB but not the Arc B570 10GB: gemma-3-12b-it (12.2B). MSRP is $219 for the Arc B570 10GB 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. In the Q4/8K head-to-head below (38 shared models), the RTX 5070 12GB posts the higher tok/s in 37 rows vs 1. Methodology.