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RTX 3090 24GB vs RTX 4090 24GB for Local LLMs

The RTX 4090 24GB has about 8% more memory bandwidth (1,008 vs 936 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 8% 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 $1,499 for the RTX 3090 24GB vs $1,599 for the RTX 4090 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 3090 24GBRTX 4090 24GB
VendorNVIDIANVIDIA
VRAM24 GB24 GB
Memory typeGDDR6XGDDR6X
Memory bandwidth936 GB/s1,008 GB/s
TDP350 W450 W
MSRP (list)$1,499$1,599
BuyMSI GeForce RTX 3090 Ventus 3X 24G OC (affiliate) · More listingsGIGABYTE GeForce RTX 4090 Gaming OC 24GB (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 3090 24GB tok/sRTX 3090 24GB fitsRTX 4090 24GB tok/sRTX 4090 24GB fitsWinner
Qwen3-0.6B0.8744.5 est.Yes801.8 est.YesRTX 4090 24GB
gemma-3-1b-it1.0595.6 est.Yes641.5 est.YesRTX 4090 24GB
Llama-3.2-1B-Instruct1.2496.4 est.Yes534.5 est.YesRTX 4090 24GB
Qwen3-1.7B2.0297.8 est.Yes320.7 est.YesRTX 4090 24GB
gpt-oss-20b21.5161.8 measuredYes225.2 measuredYesRTX 4090 24GB
Qwen3-30B-A3B30.5198.5 est.Yes213.8 est.YesRTX 4090 24GB
Qwen3-Coder-30B-A3B-Instruct30.5198.5 est.Yes213.8 est.YesRTX 4090 24GB
GLM-4.7-Flash31.2198.5 est.Yes213.8 est.YesRTX 4090 24GB
Qwen3-30B-A3B-Instruct-250730.5198.5 est.Yes213.8 est.YesRTX 4090 24GB
Llama-3.2-3B-Instruct3.2186.1 est.Yes200.5 est.YesRTX 4090 24GB
Mistral-7B-Instruct-v0.37.270.0 measuredYes183.3 measuredYesRTX 4090 24GB
Qwen3-Coder-Next79.7158.2 est.No170.4 est.NoRTX 4090 24GB
Phi-4-mini-instruct3.8156.7 est.Yes168.8 est.YesRTX 4090 24GB
Phi-4-mini-reasoning3.8156.7 est.Yes168.8 est.YesRTX 4090 24GB
gemma-3-4b-it4.3152.7 est.Yes164.5 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 3090 24GBRTX 4090 24GB
Catalog models that fit33 of 6133 of 61
Largest exclusive fit——

RTX 3090 24GB details → · RTX 4090 24GB details →