RTX 4070 12GB vs RX 7900 XTX 24GB for Local LLMs

The RX 7900 XTX 24GB has about 90% more memory bandwidth (960 vs 504 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 90% faster on the RX 7900 XTX 24GB. The RX 7900 XTX 24GB fits more of the catalog at Q4/8K — 33 vs 18 of 61 models (24 vs 12 GB VRAM). Largest model that fits the RX 7900 XTX 24GB but not the RTX 4070 12GB: GLM-4.7-Flash (31.2B). MSRP is $599 for the RTX 4070 12GB vs $999 for the RX 7900 XTX 24GB. 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 RX 7900 XTX 24GB posts the higher tok/s in 34 rows vs 6. Methodology.

Spec comparison

	RTX 4070 12GB	RX 7900 XTX 24GB
Vendor	NVIDIA	AMD
VRAM	12 GB	24 GB
Memory type	GDDR6X	GDDR6
Memory bandwidth	504 GB/s	960 GB/s
TDP	200 W	355 W
MSRP (list)	$599	$999
Buy	ASUS Dual GeForce RTX 4070 OC 12GB (affiliate) · More listings	ASRock Radeon RX 7900 XTX Phantom Gaming 24GB OC (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

Model	Params (B)	RTX 4070 12GB tok/s	RTX 4070 12GB fits	RX 7900 XTX 24GB tok/s	RX 7900 XTX 24GB fits	Winner
Qwen3-0.6B	0.8	400.9 est.	Yes	763.6 est.	Yes	RX 7900 XTX 24GB
gemma-3-1b-it	1.0	320.7 est.	Yes	610.9 est.	Yes	RX 7900 XTX 24GB
Llama-3.2-1B-Instruct	1.2	267.3 est.	Yes	509.1 est.	Yes	RX 7900 XTX 24GB
Qwen3-1.7B	2.0	160.4 est.	Yes	305.5 est.	Yes	RX 7900 XTX 24GB
Qwen3-30B-A3B	30.5	130.2 est.	No	203.6 est.	Yes	RX 7900 XTX 24GB
Qwen3-Coder-30B-A3B-Instruct	30.5	130.2 est.	No	203.6 est.	Yes	RX 7900 XTX 24GB
GLM-4.7-Flash	31.2	125.0 est.	No	203.6 est.	Yes	RX 7900 XTX 24GB
Qwen3-30B-A3B-Instruct-2507	30.5	130.2 est.	No	203.6 est.	Yes	RX 7900 XTX 24GB
gpt-oss-20b	21.5	199.6 est.	No	169.7 est.	Yes	RTX 4070 12GB
Llama-3.2-3B-Instruct	3.2	160.7 measured	Yes	190.9 est.	Yes	RX 7900 XTX 24GB
Qwen3-Coder-Next	79.7	21.3 est.	No	162.3 est.	No	RX 7900 XTX 24GB
Phi-4-mini-instruct	3.8	84.4 est.	Yes	160.8 est.	Yes	RX 7900 XTX 24GB
Phi-4-mini-reasoning	3.8	84.4 est.	Yes	160.8 est.	Yes	RX 7900 XTX 24GB
gemma-3-4b-it	4.3	82.2 est.	Yes	156.6 est.	Yes	RX 7900 XTX 24GB
Qwen3-Next-80B-A3B-Instruct	81.3	20.5 est.	No	156.2 est.	No	RX 7900 XTX 24GB

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 4070 12GB	RX 7900 XTX 24GB
Catalog models that fit	18 of 61	33 of 61
Largest exclusive fit	—	GLM-4.7-Flash (31.2B)

RTX 4070 12GB details → · RX 7900 XTX 24GB details →