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RTX 3070 8GB vs RTX 4070 12GB for Local LLMs

The RTX 4070 12GB has about 12% more memory bandwidth (504 vs 448 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 12% faster on the RTX 4070 12GB. The RTX 4070 12GB fits more of the catalog at Q4/8K — 18 vs 17 of 61 models (12 vs 8 GB VRAM). Largest model that fits the RTX 4070 12GB but not the RTX 3070 8GB: gemma-3-12b-it (12.2B). MSRP is $499 for the RTX 3070 8GB vs $599 for the RTX 4070 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 (38 shared models), the RTX 4070 12GB posts the higher tok/s in 37 rows vs 1. Methodology.

Spec comparison

RTX 3070 8GBRTX 4070 12GB
VendorNVIDIANVIDIA
VRAM8 GB12 GB
Memory typeGDDR6GDDR6X
Memory bandwidth448 GB/s504 GB/s
TDP220 W200 W
MSRP (list)$499$599
BuySearch Amazon (affiliate)ASUS Dual GeForce RTX 4070 OC 12GB (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 38 shared models

ModelParams (B)RTX 3070 8GB tok/sRTX 3070 8GB fitsRTX 4070 12GB tok/sRTX 4070 12GB fitsWinner
Qwen3-0.6B0.8356.4 est.Yes400.9 est.YesRTX 4070 12GB
gemma-3-1b-it1.0285.1 est.Yes320.7 est.YesRTX 4070 12GB
Llama-3.2-1B-Instruct1.2237.6 est.Yes267.3 est.YesRTX 4070 12GB
gpt-oss-20b21.578.9 est.No199.6 est.NoRTX 4070 12GB
Llama-3.2-3B-Instruct3.289.1 est.Yes160.7 measuredYesRTX 4070 12GB
Qwen3-1.7B2.0142.5 est.Yes160.4 est.YesRTX 4070 12GB
Qwen3-30B-A3B30.551.4 est.No130.2 est.NoRTX 4070 12GB
Qwen3-Coder-30B-A3B-Instruct30.551.4 est.No130.2 est.NoRTX 4070 12GB
Qwen3-30B-A3B-Instruct-250730.551.4 est.No130.2 est.NoRTX 4070 12GB
GLM-4.7-Flash31.249.4 est.No125.0 est.NoRTX 4070 12GB
Phi-4-mini-instruct3.875.0 est.Yes84.4 est.YesRTX 4070 12GB
Phi-4-mini-reasoning3.875.0 est.Yes84.4 est.YesRTX 4070 12GB
gemma-3-4b-it4.373.1 est.Yes82.2 est.YesRTX 4070 12GB
Qwen3-4B-Instruct-25074.071.3 est.Yes80.2 est.YesRTX 4070 12GB
Qwen3-4B-Thinking-25074.071.3 est.Yes80.2 est.YesRTX 4070 12GB

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 4070 12GB
Catalog models that fit17 of 6118 of 61
Largest exclusive fit—gemma-3-12b-it (12.2B)

RTX 3070 8GB details → · RTX 4070 12GB details →