Arc Pro B70 32GB vs RX 7900 XT 20GB for Local LLMs
The RX 7900 XT 20GB has about 32% more memory bandwidth (800 vs 608 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 32% faster on the RX 7900 XT 20GB. The Arc Pro B70 32GB fits more of the catalog at Q4/8K — 39 vs 30 of 69 models (32 vs 20 GB VRAM). Largest model that fits the Arc Pro B70 32GB but not the RX 7900 XT 20GB: Qwen3.6-35B-A3B (36.0B). MSRP is $999 for the Arc Pro B70 32GB 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 (50 shared models), the RX 7900 XT 20GB posts the higher tok/s in 39 rows vs 11. Methodology.