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RTX 3070 8GB vs RTX 5090 32GB for Local LLMs

The RTX 5090 32GB has about 300% more memory bandwidth (1,792 vs 448 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 300% faster on the RTX 5090 32GB. The RTX 5090 32GB fits more of the catalog at Q4/8K — 38 vs 17 of 61 models (32 vs 8 GB VRAM). Largest model that fits the RTX 5090 32GB but not the RTX 3070 8GB: Mixtral-8x7B-Instruct-v0.1 (46.7B). MSRP is $499 for the RTX 3070 8GB vs $1,999 for the RTX 5090 32GB. 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 5090 32GB posts the higher tok/s in 38 rows vs 0. Methodology.

Spec comparison

RTX 3070 8GBRTX 5090 32GB
VendorNVIDIANVIDIA
VRAM8 GB32 GB
Memory typeGDDR6GDDR7
Memory bandwidth448 GB/s1,792 GB/s
TDP220 W575 W
MSRP (list)$499$1,999
BuySearch Amazon (affiliate)Search Amazon (affiliate)

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 38 shared models

ModelParams (B)RTX 3070 8GB tok/sRTX 3070 8GB fitsRTX 5090 32GB tok/sRTX 5090 32GB fitsWinner
Qwen3-0.6B0.8356.4 est.Yes1425.5 est.YesRTX 5090 32GB
gemma-3-1b-it1.0285.1 est.Yes1140.4 est.YesRTX 5090 32GB
Llama-3.2-1B-Instruct1.2237.6 est.Yes950.3 est.YesRTX 5090 32GB
Qwen3-1.7B2.0142.5 est.Yes570.2 est.YesRTX 5090 32GB
Qwen3-30B-A3B30.551.4 est.No380.1 est.YesRTX 5090 32GB
Qwen3-Coder-30B-A3B-Instruct30.551.4 est.No380.1 est.YesRTX 5090 32GB
GLM-4.7-Flash31.249.4 est.No380.1 est.YesRTX 5090 32GB
Qwen3-30B-A3B-Instruct-250730.551.4 est.No380.1 est.YesRTX 5090 32GB
Llama-3.2-3B-Instruct3.289.1 est.Yes356.4 est.YesRTX 5090 32GB
Phi-4-mini-instruct3.875.0 est.Yes300.1 est.YesRTX 5090 32GB
Phi-4-mini-reasoning3.875.0 est.Yes300.1 est.YesRTX 5090 32GB
gemma-3-4b-it4.373.1 est.Yes292.4 est.YesRTX 5090 32GB
Qwen3-4B-Instruct-25074.071.3 est.Yes285.1 est.YesRTX 5090 32GB
Qwen3-4B-Thinking-25074.071.3 est.Yes285.1 est.YesRTX 5090 32GB
gpt-oss-20b21.578.9 est.No282.5 measuredYesRTX 5090 32GB

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 3070 8GBRTX 5090 32GB
Catalog models that fit17 of 6138 of 61
Largest exclusive fit—Mixtral-8x7B-Instruct-v0.1 (46.7B)

RTX 3070 8GB details → · RTX 5090 32GB details →