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A100 80GB SXM4 vs RX 7900 XT 20GB for Local LLMs

The A100 80GB SXM4 has about 155% more memory bandwidth (2,039 vs 800 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 155% faster on the A100 80GB SXM4. The A100 80GB SXM4 fits more of the catalog at Q4/8K — 46 vs 32 of 61 models (80 vs 20 GB VRAM). Largest model that fits the A100 80GB SXM4 but not the RX 7900 XT 20GB: gpt-oss-120b (120.4B). MSRP is $15,000 for the A100 80GB SXM4 vs $899 for the RX 7900 XT 20GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price. Not retail-shoppable: A100 80GB SXM4 (datacenter-class; cloud rental is the realistic way to use it). In the Q4/8K head-to-head below (46 shared models), the A100 80GB SXM4 posts the higher tok/s in 46 rows vs 0. Methodology.

Spec comparison

A100 80GB SXM4RX 7900 XT 20GB
VendorNVIDIAAMD
VRAM80 GB20 GB
Memory typeHBM2eGDDR6
Memory bandwidth2,039 GB/s800 GB/s
TDP400 W315 W
MSRP (list)$15,000$899
BuySearch 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 46 shared models

ModelParams (B)A100 80GB SXM4 tok/sA100 80GB SXM4 fitsRX 7900 XT 20GB tok/sRX 7900 XT 20GB fitsWinner
Qwen3-0.6B0.81621.9 est.Yes636.4 est.YesA100 80GB SXM4
gemma-3-1b-it1.01297.5 est.Yes509.1 est.YesA100 80GB SXM4
Llama-3.2-1B-Instruct1.21081.3 est.Yes424.2 est.YesA100 80GB SXM4
Qwen3-1.7B2.0648.8 est.Yes254.5 est.YesA100 80GB SXM4
Qwen3-30B-A3B30.5432.5 est.Yes169.7 est.YesA100 80GB SXM4
Qwen3-Coder-30B-A3B-Instruct30.5432.5 est.Yes169.7 est.YesA100 80GB SXM4
GLM-4.7-Flash31.2432.5 est.Yes169.7 est.YesA100 80GB SXM4
Qwen3-30B-A3B-Instruct-250730.5432.5 est.Yes169.7 est.YesA100 80GB SXM4
Qwen3-Next-80B-A3B-Instruct81.3432.5 est.Yes90.4 est.NoA100 80GB SXM4
Qwen3-Coder-Next79.7432.5 est.Yes93.9 est.NoA100 80GB SXM4
Llama-3.2-3B-Instruct3.2405.5 est.Yes131.2 measuredYesA100 80GB SXM4
gpt-oss-20b21.5360.4 est.Yes141.4 est.YesA100 80GB SXM4
Phi-4-mini-instruct3.8341.5 est.Yes134.0 est.YesA100 80GB SXM4
Phi-4-mini-reasoning3.8341.5 est.Yes134.0 est.YesA100 80GB SXM4
gemma-3-4b-it4.3332.7 est.Yes130.5 est.YesA100 80GB SXM4

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

A100 80GB SXM4RX 7900 XT 20GB
Catalog models that fit46 of 6132 of 61
Largest exclusive fitgpt-oss-120b (120.4B)

A100 80GB SXM4 details → · RX 7900 XT 20GB details →