Is the RTX 4090 worth it for local LLMs in 2026?

For most buyers, no. As of September 2026 a used RTX 4090 sells for about $2,600 (GetPCParts: $2,589 30-day average of eBay sold listings, $2,510 on 2026-09-19). That is 1.6x its $1,599 launch price. Its 1,008 GB/s of bandwidth costs $2.57 per GB/s, more than a used RTX 3090 ($1.56) and more than an RTX 5090 at its $4,299 floor ($2.40). It is worth it if you need fast prefill for long-context agents on 24GB with CUDA, and a 5090 is out of budget. For chat on 24GB, a used 3090 at $1,463 generates only about 15% slower in community llama.cpp tests.

How good is RTX 4090 LLM performance?

Very good for any model that fits in 24GB. Community llama-bench results: 271 tok/s generation on Qwen3 30B-A3B Q4_K and 272 tok/s on gpt-oss 20B MXFP4 (llama.cpp discussion #17621, November 2025, with CUDA graph optimizations on). On the llama.cpp CUDA scoreboard (discussion #15013) it measured 186-189 tok/s generation and 12,000-14,800 tok/s prompt processing on Llama 2 7B Q4_0. It cannot load Llama 3.3 70B at Q4_K_M (42.5GB) on one card.

RTX 4090 vs RTX 5090 for LLMs: which is better value?

At September 2026 prices, the RTX 5090 is better value per unit of speed, and the 4090 is cheaper to buy. A used 4090 costs about $2,600; the 5090 costs $4,299 at the lowest reputable seller, 1.66x more. The 5090 has 1.78x the bandwidth (1,792 against 1,008 GB/s) and 8GB more memory. In community llama.cpp tests it generated 1.3-1.56x faster. Per GB/s the 5090 costs $2.40 and the 4090 $2.57. Buy the 4090 only if $4,299 is outside your budget.

3090 vs 4090 for local LLM: is the upgrade worth it?

For chat, no. For long prompts, sometimes. On the llama.cpp CUDA scoreboard the 4090 generated 17-18% faster than the 3090 on Llama 2 7B Q4_0 (186-189 against 158-162 tok/s), and processed prompts 2.3-2.7x faster. As of September 2026 a used 4090 costs about $2,600 and a used 3090 about $1,463, so the 4090 costs 1.77x as much. Both cards have 24GB, so they run the same models.

4090 or R9700 for local AI?

The R9700 for capacity, the 4090 for speed and CUDA. The Radeon AI PRO R9700 has 32GB at 640 GB/s for a $1,299 MSRP (street average about $1,599, as of September 2026). The used 4090 has 24GB at 1,008 GB/s for about $2,600. The R9700 costs $41-50 per GB of VRAM and the 4090 $108. Two R9700s at MSRP ($2,598) give 64GB for the price of one used 4090 and can hold Llama 3.3 70B Q4_K_M. The 4090 has 1.58x the bandwidth and runs every CUDA tool without porting.

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Hardware September 25, 2026

Is the RTX 4090 Worth $2,600 for Local LLMs? (2026)

The RTX 4090 launched at $1,599 in October 2022, and NVIDIA stopped making it in late 2024. As of September 2026 a used one sells for about $2,600 on eBay, and new stock costs $3,200 or more. That is more per GB/s of bandwidth than a new RTX 5090 at its $4,299 floor. This page gives the verdict at today's price for each type of buyer, shows what the same money buys instead, and works out how many rental hours the card has to replace.

Bottom Line

A used RTX 4090 costs about $2,600 as of September 2026. That is 1.6x its $1,599 launch price from 2022. Whether it is worth that depends on who you are.

Buyer	Worth ~$2,600?	Why
You run long-context agents or coding on 24GB, need CUDA, and cannot spend $4,299	Yes	It processes prompts 2.3-2.7x faster than a 3090 in community llama.cpp tests. Long prompts wait less.
You already own one	Yes, keep it	It resells above its launch price. Nothing new under $4,000 is faster on CUDA.
You chat with 20-35B models	No	A used RTX 3090 ($1,463) has the same 24GB and generates only about 15% slower, for 56% of the price.
You want 70B dense or 100B+ MoE models	No	24GB cannot hold Llama 3.3 70B Q4_K_M (42.5GB). Two R9700s at MSRP ($2,598) give 64GB for the same money.
You can stretch to $4,299	No	The RTX 5090 costs less per GB/s ($2.40 against $2.57) and adds 8GB.
You use local AI a few hours a week	No	RunPod rents a 4090 for $0.34-0.74 per hour. The card needs about 3,930 hours of use to beat the higher rate.

The short version: at 2026 prices the 4090 has the most expensive memory bandwidth of the four 24-32GB cards we price. It costs more per GB/s than a used 3090, an R9700, and even a new RTX 5090 at its $4,299 floor. It sits between those cards on speed, but not on value. Buy it only for prefill speed on 24GB, at a budget that stops short of a 5090.

The price as of September 2026

NVIDIA told board partners to stop RTX 4090 production by October 2024 (TweakTown, 2024-10-06, citing Board Channels). New stock is now leftover inventory. The prices we found tonight:

Measure	Price	Date	Source
Launch MSRP (Founders Edition)	$1,599	12 Oct 2022	Wikipedia, GeForce RTX 40 series
Used, latest eBay sold reading	$2,510	2026-09-19	GetPCParts
Used, 30-day average of eBay sold readings	$2,589	to 2026-09-19	GetPCParts (5 readings)
Used, highest reading this year	$3,010	2026-09-12	GetPCParts
Used, eBay US median	$3,000	2026-09-25	ResalePrices (17 listings, 90-day range $2,497-3,075, +20% in 30 days)
New, Amazon	$3,200	read 2026-09-25	GPUDojo
New, Newegg	$4,499	read 2026-09-25	GPUDojo
August 2026 used range (our earlier read)	$2,270-2,600	August 2026	ResalePrices / BestValueGPU

We use $2,589 (the GetPCParts 30-day sold average) as the working price on this page. ResalePrices shows $3,000, but from only 17 listings. GPUDojo also lists an eBay “new” price of $2,073. We treat that as one marketplace listing, not a market price.

The 4090 sells above its launch price, and the gap is growing. At $2,589 it costs 162% of its $1,599 MSRP. A used RTX 3090 sells at 97% of its launch price. The cause is the 2026 memory shortage, plus a card that no one makes any more. Prices can also fall. A card at 1.6x its own MSRP has room to drop if new-card prices ease.

If you buy, compare the listing against the $2,500-2,600 sold range first. The catalog pick is the RTX 4090 24GB. Check the listed price: it moves between $3,200 and $4,500 new.

What $2,600 buys instead

All prices as of September 2026. Dollars per GB and per GB/s are our arithmetic, with the same method as our RTX 5090 and RTX 3090 verdicts. Bandwidth comes from vendor spec sheets.

Option	Price	Memory	Bandwidth	$ per GB	$ per GB/s	Holds Llama 3.3 70B Q4_K_M (42.5GB)?
Used RTX 4090	$2,589	24GB GDDR6X	1,008 GB/s	$108	$2.57	No
Used RTX 3090	$1,463 avg	24GB GDDR6X	936 GB/s	$61	$1.56	No
2x used RTX 3090	$2,926	48GB	936 GB/s each	$61	n/a	Yes
Radeon AI PRO R9700	$1,299 MSRP; $1,599 street avg	32GB GDDR6	640 GB/s	$41 at MSRP; $50 street	$2.03 at MSRP; $2.50 street	No
2x R9700	$2,598 at MSRP	64GB	640 GB/s each	$41	n/a	Yes
RTX 5060 Ti 16GB (new)	$789 (B&H, 2026-09-24)	16GB GDDR7	448 GB/s	$49	$1.76	No
RTX 5090 (new)	$4,299 floor (2026-09-22)	32GB GDDR7	1,792 GB/s	$134	$2.40	No
RunPod RTX 4090 rental	$0.34-0.74/hr	24GB	1,008 GB/s	n/a	n/a	No

Three things stand out.

On capacity, the 4090 is the second-worst buy. At $108 per GB it costs 1.8x a used 3090 per GB. Only the 5090 costs more, at $134.
On bandwidth, the 4090 is the worst buy. At $2.57 per GB/s it costs more than the 5090 ($2.40), the R9700 at street price ($2.50) and the 3090 ($1.56). Token generation speed follows bandwidth.
The exact price of one used 4090 buys two R9700s at MSRP. That is 64GB against 24GB. It holds a 70B model at Q4_K_M. Stock is the catch: Newegg showed the R9700 out of stock on 2026-09-24.

The three alternatives, in numbers

Used RTX 3090. Same 24GB, same model fit. Its 936 GB/s is 93% of the 4090’s 1,008 GB/s. On the llama.cpp CUDA scoreboard it generated 158-162 tok/s on Llama 2 7B Q4_0, against 186-189 for the 4090. ResalePrices shows a $1,463 average across 291 eBay US listings on 2026-09-24. A used RTX 3090 24GB costs 56% of a 4090. Pick a model with which used RTX 3090 to buy.

RTX 5090. It costs 1.66x the used 4090 ($4,299 against $2,589). It has 1.78x the bandwidth and 8GB more memory. In community tests it generated 1.3-1.56x faster (details below). NVIDIA still sells new 5090s with a warranty. Used 4090s have none from the seller. If you can reach $4,299 from a first-party seller, the RTX 5090 is the better use of money. The verdict is in is the RTX 5090 worth it.

Radeon AI PRO R9700 32GB. It has 8GB more than the 4090 at 50-62% of the price. It has 63% of the 4090’s bandwidth (640 against 1,008 GB/s), so expect slower generation on a model that fits both. That is a bandwidth-ratio estimate, not a measurement. It runs on ROCm, not CUDA. Buy the Radeon AI PRO R9700 32GB near its $1,299 MSRP. The comparison against the 3090 is in R9700 vs RTX 3090.

RTX 4090 LLM performance on models that fit in 24GB

All numbers below are community-reported llama-bench results from the llama.cpp GitHub discussions. They are not our measurements.

Model	Test	RTX 3090	RTX 4090	RTX 5090	Source
Llama 2 7B Q4_0	Generation (tg128), FA off	158.2 tok/s	186.2 tok/s	290.0 tok/s	Discussion #15013
Llama 2 7B Q4_0	Prompt (pp512), FA off	5,175 tok/s	11,993 tok/s	14,073 tok/s	Discussion #15013
Llama 2 7B Q4_0	Generation, FA on	161.9 tok/s	189.0 tok/s	not listed	Discussion #15013
Llama 2 7B Q4_0	Prompt, FA on	5,560 tok/s	14,771 tok/s	not listed	Discussion #15013
Qwen3 30B-A3B Q4_K	Generation, CUDA graph opt on	not tested	271.0 tok/s	352.1 tok/s	Discussion #17621 (Nov 2025)
gpt-oss 20B MXFP4	Generation, CUDA graph opt on	not tested	272.0 tok/s	419.1 tok/s	Discussion #17621 (Nov 2025)

The 3090 and 4090 rows on the scoreboard come from different llama.cpp builds. Read them as a guide, not an exact ratio.

What the numbers say:

Generation: the 4090 is only 17-18% faster than a 3090. 186.2 / 158.2 = 1.18. 189.0 / 161.9 = 1.17. The bandwidth gap is 8% (1,008 / 936).
Prompt processing: the 4090 is 2.3-2.7x faster than a 3090. 11,993 / 5,175 = 2.3. 14,771 / 5,560 = 2.7. This is where the extra money goes.
The 5090 is 1.3-1.56x faster than the 4090 at generation. 290.0 / 186.2 = 1.56. 352.1 / 271.0 = 1.30. 419.1 / 272.0 = 1.54.

Now divide the price by the Llama 2 7B generation speed (FA off). Our arithmetic:

Used RTX 3090: $1,463 / 158.2 = $9.25 per tok/s
Used RTX 4090: $2,589 / 186.2 = $13.90 per tok/s
RTX 5090: $4,299 / 290.0 = $14.82 per tok/s

The 4090 costs 50% more per unit of generation speed than the 3090. It costs only 6% less than the 5090.

What 24GB runs

File sizes from the Hugging Face API, as listed on our RTX 3090 verdict (read 2026-09-24).

Model	Quant	File size	Fits 24GB?	4090 generation
gpt-oss 20B	native MXFP4	13.8GB	Yes	272 tok/s (community, #17621)
Qwen3.6 27B	Q4_K_M	16.8GB	Yes	~48 tok/s (our estimate, below)
Qwen3.6 35B-A3B	MXFP4_MOE	21.7GB	Yes, with little context room	not measured
Llama 3.3 70B	Q4_K_M	42.5GB	No	n/a
gpt-oss 120B	MXFP4	65.4GB	No	n/a

The Qwen3.6 27B figure is an estimate. A dense model reads its full weights for each token. 1,008 GB/s / 16.8GB = 60 tok/s as a ceiling. The #17621 author reached about 80% of theoretical bandwidth on a 5090. 60 x 0.8 = 48 tok/s. The model picks for this card are in best local LLM for the RTX 4090. For 70B, read can an RTX 4090 run a 70B model.

Rent vs buy

RunPod lists the RTX 4090 at $0.74 per hour on Secure Cloud and $0.34 on Community Cloud (runpod.io/pricing, read 2026-09-22). Owning the card also costs power. NVIDIA rates the 4090 at 450W total graphics power. At $0.18/kWh (US average, as of August 2026), that is about $0.08 per hour under load.

Our arithmetic, for $2,589:

Rental rate	Net saving per hour of ownership	Break-even hours	At 4 h/day	At 8 h/day	24/7
$0.74 (Secure)	$0.66	~3,930	2.7 years	1.3 years	5.4 months
$0.34 (Community)	$0.26	~10,000	6.8 years	3.4 years	13.7 months

The formula is $2,589 / ($0.74 - $0.081) = 3,929 hours. At the Community rate it is $2,589 / ($0.34 - $0.081) = 9,996 hours.

Two things favor buying. A card you own keeps resale value, and today’s resale value is above launch price. Your prompts also never leave your machine. One thing favors renting: the 4090 is nearly four years old and has no seller warranty. If you cannot name the job that fills 4 hours a day, rent for a month and log your hours first.

Is the RTX 4090 worth it over a used RTX 3090?

For chat, no. Both cards hold the same 24GB and run the same models. The 4090 generates 17-18% faster and costs 1.77x as much ($2,589 / $1,463).

For agents and coding, sometimes. Agent loops resend 20-30K tokens of context on every call. The 4090 processes prompts 2.3-2.7x faster than a 3090 on the scoreboard test. If your work waits on prompt processing, the 4090 pays for that wait. The full head-to-head is in RTX 3090 vs RTX 4090.

Is the RTX 4090 worth it over an RTX 5090?

Only if $4,299 is outside your budget. The 5090 costs 1.66x the used 4090. It gives 1.78x the bandwidth, 1.33x the memory (32GB against 24GB), and a new-card warranty. Per GB/s it is the cheaper card. The three-way comparison is in RTX 5090 vs 4090 vs used 3090.

Power and fit

NVIDIA rates the 4090 at 450W and specifies an 850W minimum system power supply. A used card has no warranty from the seller. Stress-test it before the return window closes. Our used RTX 3090 checklist applies to the 4090 as well.

Sources

GetPCParts: used RTX 4090 eBay sold prices, read 2026-09-25 (latest reading 2026-09-19)
ResalePrices: used RTX 4090 eBay US market, updated 2026-09-25
GPUDojo: RTX 4090 new prices by retailer, read 2026-09-25
TweakTown: NVIDIA to cease RTX 4090 production by October 2024, 2024-10-06
NVIDIA GeForce RTX 4090 specifications (24GB GDDR6X, 384-bit, 450W, 850W system power)
Wikipedia: GeForce RTX 40 series (launch 12 Oct 2022, $1,599 MSRP, 1,008 GB/s)
llama.cpp discussion #15013: performance of llama.cpp on NVIDIA CUDA (community-reported)
llama.cpp discussion #17621: optimizing token generation in the CUDA backend, 2025-11-30 (community-reported)
ResalePrices: used RTX 3090 eBay US market, read 2026-09-24
Tom’s Hardware: MSI RTX 5090 for $4,299 at Walmart, 2026-09-22
AMD Radeon AI PRO R9700 specifications (32GB, 640 GB/s)
runaihome: R9700 street price tracking, September 2026
gpuprix: RTX 5060 Ti 16GB US price, read 2026-09-24
RunPod GPU pricing, read 2026-09-22
Model file sizes from the Hugging Face API: unsloth/gpt-oss-20b-GGUF, unsloth/Qwen3.6-27B-GGUF, unsloth/Qwen3.6-35B-A3B-GGUF, bartowski/Llama-3.3-70B-Instruct-GGUF, unsloth/gpt-oss-120b-GGUF