The RTX 4090 24GB has about 84% more memory bandwidth (1,008 vs 548 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 84% faster on the RTX 4090 24GB. The RTX 4090 24GB fits more of the catalog at Q4/8K — 35 vs 18 of 69 models (24 vs 12 GB VRAM). Largest model that fits the RTX 4090 24GB but not the Titan Xp 12GB: Qwen3.6-35B-A3B (36.0B). MSRP is $1,599 for the RTX 4090 24GB vs $1,200 for the Titan Xp 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 (41 shared models), the RTX 4090 24GB posts the higher tok/s in 41 rows vs 0. Methodology.