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RTX 4090 24GB vs RX 7900 XTX 24GB for Local LLMs

The RTX 4090 24GB has about 5% more memory bandwidth (1,008 vs 960 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 5% faster on the RTX 4090 24GB. Both fit the same number of catalog models at Q4/8K (33 of 61; 24 vs 24 GB VRAM). MSRP is $1,599 for the RTX 4090 24GB vs $999 for the RX 7900 XTX 24GB. 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 (47 shared models), the RTX 4090 24GB posts the higher tok/s in 45 rows vs 2. Methodology.

Spec comparison

RTX 4090 24GBRX 7900 XTX 24GB
VendorNVIDIAAMD
VRAM24 GB24 GB
Memory typeGDDR6XGDDR6
Memory bandwidth1,008 GB/s960 GB/s
TDP450 W355 W
MSRP (list)$1,599$999
BuyGIGABYTE GeForce RTX 4090 Gaming OC 24GB (affiliate) · More listingsASRock Radeon RX 7900 XTX Phantom Gaming 24GB OC (affiliate) · More listings

MSRP is the launch list price, not live retail. Buy links are Amazon affiliate links — the price after you click is the live price.

Q4 / 8K head-to-head — top 15 of 47 shared models

ModelParams (B)RTX 4090 24GB tok/sRTX 4090 24GB fitsRX 7900 XTX 24GB tok/sRX 7900 XTX 24GB fitsWinner
Qwen3-0.6B0.8801.8 est.Yes763.6 est.YesRTX 4090 24GB
gemma-3-1b-it1.0641.5 est.Yes610.9 est.YesRTX 4090 24GB
Llama-3.2-1B-Instruct1.2534.5 est.Yes509.1 est.YesRTX 4090 24GB
Qwen3-1.7B2.0320.7 est.Yes305.5 est.YesRTX 4090 24GB
gpt-oss-20b21.5225.2 measuredYes169.7 est.YesRTX 4090 24GB
Qwen3-30B-A3B30.5213.8 est.Yes203.6 est.YesRTX 4090 24GB
Qwen3-Coder-30B-A3B-Instruct30.5213.8 est.Yes203.6 est.YesRTX 4090 24GB
GLM-4.7-Flash31.2213.8 est.Yes203.6 est.YesRTX 4090 24GB
Qwen3-30B-A3B-Instruct-250730.5213.8 est.Yes203.6 est.YesRTX 4090 24GB
Llama-3.2-3B-Instruct3.2200.5 est.Yes190.9 est.YesRTX 4090 24GB
Mistral-7B-Instruct-v0.37.2183.3 measuredYes68.0 measuredYesRTX 4090 24GB
Qwen3-Coder-Next79.7170.4 est.No162.3 est.NoRTX 4090 24GB
Phi-4-mini-instruct3.8168.8 est.Yes160.8 est.YesRTX 4090 24GB
Phi-4-mini-reasoning3.8168.8 est.Yes160.8 est.YesRTX 4090 24GB
gemma-3-4b-it4.3164.5 est.Yes156.6 est.YesRTX 4090 24GB

est. = bandwidth-based estimate; measured = curated real benchmark that overrides the estimate. Fits = weights + KV(8K) + 1 GB overhead ≤ 95% of VRAM.

Fit coverage at Q4 / 8K

RTX 4090 24GBRX 7900 XTX 24GB
Catalog models that fit33 of 6133 of 61
Largest exclusive fit——

RTX 4090 24GB details → · RX 7900 XTX 24GB details →