Question 1

Is the RTX 3090 Ti 24GB or the RTX 4090 24GB better for local LLMs?

Accepted Answer

Both list the same memory bandwidth (1,008 GB/s), so per-token decode speed should be similar whenever a model fits both. Both fit the same number of catalog models at Q4/8K (33 of 61; 24 vs 24 GB VRAM). MSRP is $1,999 for the RTX 3090 Ti 24GB vs $1,599 for the RTX 4090 24GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price.

Question 2

How much faster is the RTX 3090 Ti 24GB than the RTX 4090 24GB for LLM inference?

Accepted Answer

Both list the same memory bandwidth (1,008 GB/s), so decode speed should be very close when a model fits both. Head-to-head at Q4/8K: 3–8 of 47 shared rows.

Question 3

Which can run larger models, the RTX 3090 Ti 24GB or the RTX 4090 24GB?

Accepted Answer

Neither — both fit 33 of 61 catalog models at Q4/8K (24 vs 24 GB VRAM).

	RTX 3090 Ti 24GB	RTX 4090 24GB
Vendor	NVIDIA	NVIDIA
VRAM	24 GB	24 GB
Memory type	GDDR6X	GDDR6X
Memory bandwidth	1,008 GB/s	1,008 GB/s
TDP	450 W	450 W
MSRP (list)	$1,999	$1,599
Buy	Search Amazon (affiliate)	GIGABYTE GeForce RTX 4090 Gaming OC 24GB (affiliate) · More listings

Model	Params (B)	RTX 3090 Ti 24GB tok/s	RTX 3090 Ti 24GB fits	RTX 4090 24GB tok/s	RTX 4090 24GB fits	Winner
Qwen3-0.6B	0.8	801.8 est.	Yes	801.8 est.	Yes	Tie
gemma-3-1b-it	1.0	641.5 est.	Yes	641.5 est.	Yes	Tie
Llama-3.2-1B-Instruct	1.2	534.5 est.	Yes	534.5 est.	Yes	Tie
Qwen3-1.7B	2.0	320.7 est.	Yes	320.7 est.	Yes	Tie
gpt-oss-20b	21.5	178.2 est.	Yes	225.2 measured	Yes	RTX 4090 24GB
Qwen3-30B-A3B	30.5	213.8 est.	Yes	213.8 est.	Yes	Tie
Qwen3-Coder-30B-A3B-Instruct	30.5	213.8 est.	Yes	213.8 est.	Yes	Tie
GLM-4.7-Flash	31.2	213.8 est.	Yes	213.8 est.	Yes	Tie
Qwen3-30B-A3B-Instruct-2507	30.5	213.8 est.	Yes	213.8 est.	Yes	Tie
Llama-3.2-3B-Instruct	3.2	200.5 est.	Yes	200.5 est.	Yes	Tie
Mistral-7B-Instruct-v0.3	7.2	89.1 est.	Yes	183.3 measured	Yes	RTX 4090 24GB
Qwen3-Coder-Next	79.7	170.4 est.	No	170.4 est.	No	Tie
Phi-4-mini-instruct	3.8	168.8 est.	Yes	168.8 est.	Yes	Tie
Phi-4-mini-reasoning	3.8	168.8 est.	Yes	168.8 est.	Yes	Tie
gemma-3-4b-it	4.3	164.5 est.	Yes	164.5 est.	Yes	Tie

RTX 3090 Ti 24GB vs RTX 4090 24GB for Local LLMs

Spec comparison

Q4 / 8K head-to-head — top 15 of 47 shared models

Fit coverage at Q4 / 8K

	RTX 3090 Ti 24GB	RTX 4090 24GB
Catalog models that fit	33 of 61	33 of 61
Largest exclusive fit	—	—