MI300X 192GB vs RX 7800 XT 16GB for Local LLMs

The MI300X 192GB has about 749% more memory bandwidth (5,300 vs 624 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 749% faster on the MI300X 192GB. The MI300X 192GB fits more of the catalog at Q4/8K — 50 vs 25 of 61 models (192 vs 16 GB VRAM). Largest model that fits the MI300X 192GB but not the RX 7800 XT 16GB: Qwen3-235B-A22B (235.1B). MSRP is $15,000 for the MI300X 192GB vs $499 for the RX 7800 XT 16GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price. Not retail-shoppable: MI300X 192GB (datacenter-class; cloud rental is the realistic way to use it). In the Q4/8K head-to-head below (44 shared models), the MI300X 192GB posts the higher tok/s in 44 rows vs 0. Methodology.

Spec comparison

	MI300X 192GB	RX 7800 XT 16GB
Vendor	AMD	AMD
VRAM	192 GB	16 GB
Memory type	HBM3	GDDR6
Memory bandwidth	5,300 GB/s	624 GB/s
TDP	750 W	263 W
MSRP (list)	$15,000	$499
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 44 shared models

Model	Params (B)	MI300X 192GB tok/s	MI300X 192GB fits	RX 7800 XT 16GB tok/s	RX 7800 XT 16GB fits	Winner
Qwen3-0.6B	0.8	4215.9 est.	Yes	496.4 est.	Yes	MI300X 192GB
gemma-3-1b-it	1.0	3372.7 est.	Yes	397.1 est.	Yes	MI300X 192GB
Llama-3.2-1B-Instruct	1.2	2810.6 est.	Yes	330.9 est.	Yes	MI300X 192GB
Qwen3-1.7B	2.0	1686.4 est.	Yes	198.5 est.	Yes	MI300X 192GB
Qwen3-30B-A3B	30.5	1124.2 est.	Yes	286.6 est.	No	MI300X 192GB
Qwen3-Coder-30B-A3B-Instruct	30.5	1124.2 est.	Yes	286.6 est.	No	MI300X 192GB
GLM-4.7-Flash	31.2	1124.2 est.	Yes	275.1 est.	No	MI300X 192GB
Qwen3-30B-A3B-Instruct-2507	30.5	1124.2 est.	Yes	286.6 est.	No	MI300X 192GB
Qwen3-Next-80B-A3B-Instruct	81.3	1124.2 est.	Yes	45.1 est.	No	MI300X 192GB
Qwen3-Coder-Next	79.7	1124.2 est.	Yes	46.9 est.	No	MI300X 192GB
Llama-3.2-3B-Instruct	3.2	1054.0 est.	Yes	124.1 est.	Yes	MI300X 192GB
gpt-oss-20b	21.5	936.9 est.	Yes	110.3 est.	Yes	MI300X 192GB
Phi-4-mini-instruct	3.8	887.6 est.	Yes	104.5 est.	Yes	MI300X 192GB
Phi-4-mini-reasoning	3.8	887.6 est.	Yes	104.5 est.	Yes	MI300X 192GB
gemma-3-4b-it	4.3	864.8 est.	Yes	101.8 est.	Yes	MI300X 192GB

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

	MI300X 192GB	RX 7800 XT 16GB
Catalog models that fit	50 of 61	25 of 61
Largest exclusive fit	Qwen3-235B-A22B (235.1B)	—

MI300X 192GB details → · RX 7800 XT 16GB details →