RTX 5090 32GB vs RX 7900 XT 20GB for Local LLMs

The RTX 5090 32GB has about 124% more memory bandwidth (1,792 vs 800 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 124% faster on the RTX 5090 32GB. The RTX 5090 32GB fits more of the catalog at Q4/8K — 38 vs 32 of 61 models (32 vs 20 GB VRAM). Largest model that fits the RTX 5090 32GB but not the RX 7900 XT 20GB: Mixtral-8x7B-Instruct-v0.1 (46.7B). MSRP is $1,999 for the RTX 5090 32GB 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. In the Q4/8K head-to-head below (46 shared models), the RTX 5090 32GB posts the higher tok/s in 44 rows vs 2. Methodology.

Spec comparison

	RTX 5090 32GB	RX 7900 XT 20GB
Vendor	NVIDIA	AMD
VRAM	32 GB	20 GB
Memory type	GDDR7	GDDR6
Memory bandwidth	1,792 GB/s	800 GB/s
TDP	575 W	315 W
MSRP (list)	$1,999	$899
Buy	Search 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 46 shared models

Model	Params (B)	RTX 5090 32GB tok/s	RTX 5090 32GB fits	RX 7900 XT 20GB tok/s	RX 7900 XT 20GB fits	Winner
Qwen3-0.6B	0.8	1425.5 est.	Yes	636.4 est.	Yes	RTX 5090 32GB
gemma-3-1b-it	1.0	1140.4 est.	Yes	509.1 est.	Yes	RTX 5090 32GB
Llama-3.2-1B-Instruct	1.2	950.3 est.	Yes	424.2 est.	Yes	RTX 5090 32GB
Qwen3-1.7B	2.0	570.2 est.	Yes	254.5 est.	Yes	RTX 5090 32GB
Qwen3-Coder-Next	79.7	538.6 est.	No	93.9 est.	No	RTX 5090 32GB
Qwen3-Next-80B-A3B-Instruct	81.3	518.3 est.	No	90.4 est.	No	RTX 5090 32GB
Qwen3-30B-A3B	30.5	380.1 est.	Yes	169.7 est.	Yes	RTX 5090 32GB
Qwen3-Coder-30B-A3B-Instruct	30.5	380.1 est.	Yes	169.7 est.	Yes	RTX 5090 32GB
GLM-4.7-Flash	31.2	380.1 est.	Yes	169.7 est.	Yes	RTX 5090 32GB
Qwen3-30B-A3B-Instruct-2507	30.5	380.1 est.	Yes	169.7 est.	Yes	RTX 5090 32GB
Llama-3.2-3B-Instruct	3.2	356.4 est.	Yes	131.2 measured	Yes	RTX 5090 32GB
Phi-4-mini-instruct	3.8	300.1 est.	Yes	134.0 est.	Yes	RTX 5090 32GB
Phi-4-mini-reasoning	3.8	300.1 est.	Yes	134.0 est.	Yes	RTX 5090 32GB
gemma-3-4b-it	4.3	292.4 est.	Yes	130.5 est.	Yes	RTX 5090 32GB
Qwen3-4B-Instruct-2507	4.0	285.1 est.	Yes	127.3 est.	Yes	RTX 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 5090 32GB	RX 7900 XT 20GB
Catalog models that fit	38 of 61	32 of 61
Largest exclusive fit	Mixtral-8x7B-Instruct-v0.1 (46.7B)	—

RTX 5090 32GB details → · RX 7900 XT 20GB details →