H100 80GB SXM5 vs RX 7900 XT 20GB for Local LLMs

The H100 80GB SXM5 has about 319% more memory bandwidth (3,350 vs 800 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 319% faster on the H100 80GB SXM5. The H100 80GB SXM5 fits more of the catalog at Q4/8K — 46 vs 32 of 61 models (80 vs 20 GB VRAM). Largest model that fits the H100 80GB SXM5 but not the RX 7900 XT 20GB: gpt-oss-120b (120.4B). MSRP is $30,000 for the H100 80GB SXM5 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: H100 80GB SXM5 (datacenter-class; cloud rental is the realistic way to use it). In the Q4/8K head-to-head below (46 shared models), the H100 80GB SXM5 posts the higher tok/s in 46 rows vs 0. Methodology.

Spec comparison

	H100 80GB SXM5	RX 7900 XT 20GB
Vendor	NVIDIA	AMD
VRAM	80 GB	20 GB
Memory type	HBM3	GDDR6
Memory bandwidth	3,350 GB/s	800 GB/s
TDP	700 W	315 W
MSRP (list)	$30,000	$899
Buy	—	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 46 shared models

Model	Params (B)	H100 80GB SXM5 tok/s	H100 80GB SXM5 fits	RX 7900 XT 20GB tok/s	RX 7900 XT 20GB fits	Winner
Qwen3-0.6B	0.8	2664.8 est.	Yes	636.4 est.	Yes	H100 80GB SXM5
gemma-3-1b-it	1.0	2131.8 est.	Yes	509.1 est.	Yes	H100 80GB SXM5
Llama-3.2-1B-Instruct	1.2	1776.5 est.	Yes	424.2 est.	Yes	H100 80GB SXM5
Qwen3-1.7B	2.0	1065.9 est.	Yes	254.5 est.	Yes	H100 80GB SXM5
Qwen3-30B-A3B	30.5	710.6 est.	Yes	169.7 est.	Yes	H100 80GB SXM5
Qwen3-Coder-30B-A3B-Instruct	30.5	710.6 est.	Yes	169.7 est.	Yes	H100 80GB SXM5
GLM-4.7-Flash	31.2	710.6 est.	Yes	169.7 est.	Yes	H100 80GB SXM5
Qwen3-30B-A3B-Instruct-2507	30.5	710.6 est.	Yes	169.7 est.	Yes	H100 80GB SXM5
Qwen3-Next-80B-A3B-Instruct	81.3	710.6 est.	Yes	90.4 est.	No	H100 80GB SXM5
Qwen3-Coder-Next	79.7	710.6 est.	Yes	93.9 est.	No	H100 80GB SXM5
Llama-3.2-3B-Instruct	3.2	666.2 est.	Yes	131.2 measured	Yes	H100 80GB SXM5
gpt-oss-20b	21.5	592.2 est.	Yes	141.4 est.	Yes	H100 80GB SXM5
Phi-4-mini-instruct	3.8	561.0 est.	Yes	134.0 est.	Yes	H100 80GB SXM5
Phi-4-mini-reasoning	3.8	561.0 est.	Yes	134.0 est.	Yes	H100 80GB SXM5
gemma-3-4b-it	4.3	546.6 est.	Yes	130.5 est.	Yes	H100 80GB SXM5

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

	H100 80GB SXM5	RX 7900 XT 20GB
Catalog models that fit	46 of 61	32 of 61
Largest exclusive fit	gpt-oss-120b (120.4B)	—

H100 80GB SXM5 details → · RX 7900 XT 20GB details →