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L40S 48GB vs RTX 4070 12GB for Local LLMs

The L40S 48GB has about 71% more memory bandwidth (864 vs 504 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 71% faster on the L40S 48GB. The L40S 48GB fits more of the catalog at Q4/8K — 39 vs 18 of 61 models (48 vs 12 GB VRAM). Largest model that fits the L40S 48GB but not the RTX 4070 12GB: Qwen3-Coder-Next (79.7B). MSRP is $8,000 for the L40S 48GB 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 (40 shared models), the L40S 48GB posts the higher tok/s in 33 rows vs 7. Methodology.

Spec comparison

L40S 48GBRTX 4070 12GB
VendorNVIDIANVIDIA
VRAM48 GB12 GB
Memory typeGDDR6GDDR6X
Memory bandwidth864 GB/s504 GB/s
TDP350 W200 W
MSRP (list)$8,000$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 40 shared models

ModelParams (B)L40S 48GB tok/sL40S 48GB fitsRTX 4070 12GB tok/sRTX 4070 12GB fitsWinner
Qwen3-0.6B0.8687.3 est.Yes400.9 est.YesL40S 48GB
Qwen3-Next-80B-A3B-Instruct81.3562.3 est.No20.5 est.NoL40S 48GB
gemma-3-1b-it1.0549.8 est.Yes320.7 est.YesL40S 48GB
Llama-3.2-1B-Instruct1.2458.2 est.Yes267.3 est.YesL40S 48GB
Qwen3-1.7B2.0274.9 est.Yes160.4 est.YesL40S 48GB
gpt-oss-20b21.5152.7 est.Yes199.6 est.NoRTX 4070 12GB
Qwen3-30B-A3B30.5183.3 est.Yes130.2 est.NoL40S 48GB
Qwen3-Coder-30B-A3B-Instruct30.5183.3 est.Yes130.2 est.NoL40S 48GB
GLM-4.7-Flash31.2183.3 est.Yes125.0 est.NoL40S 48GB
Qwen3-30B-A3B-Instruct-250730.5183.3 est.Yes130.2 est.NoL40S 48GB
Qwen3-Coder-Next79.7183.3 est.Yes21.3 est.NoL40S 48GB
Llama-3.2-3B-Instruct3.2171.8 est.Yes160.7 measuredYesL40S 48GB
Phi-4-mini-instruct3.8144.7 est.Yes84.4 est.YesL40S 48GB
Phi-4-mini-reasoning3.8144.7 est.Yes84.4 est.YesL40S 48GB
gemma-3-4b-it4.3141.0 est.Yes82.2 est.YesL40S 48GB

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

L40S 48GBRTX 4070 12GB
Catalog models that fit39 of 6118 of 61
Largest exclusive fitQwen3-Coder-Next (79.7B)

L40S 48GB details → · RTX 4070 12GB details →