Can I run gpt-oss-20b on a Dual RTX 4090?
Yes. gpt-oss-20b runs on a Dual RTX 4090: the whole model fits in its graphics memory.
We don't give a speed for this model yet. This model only uses part of itself for each word (a mixture of experts), and our speed estimate does not handle that yet.
Updated · gpt-oss-20b on every card
How much memory it needs
It uses about 28% of the memory that is free on this machine.
What a Dual RTX 4090 costs
Dual RTX 4090, 64 GB RAM$5,910€5,470price unverified
Price details
$5,910€5,470
How we priced this
- Graphics cards (2×)$4,892€4,370
- Memory, 64 GB DDR4 (estimate)$555€600
- Rest of the PC: processor, board, case, power supply, storage (estimate)$463€500
The card is the GeForce RTX 4090 24GB. Used price, the typical price of second-hand cards that actually sold. Source: pcprice.watch, checked 16 Oct 2026.
The total is our estimate from these parts, not the price of a ready-made PC in a shop.
DDR5 was not separately priced, so this total uses the price we found for 64 GB DDR4 memory.
Prices excl. shipping. Euro prices incl. VAT. Dollar prices are converted from our euro prices without EU VAT, before US sales tax.
With 128 GB of normal memory (RAM) instead of 64 GB: Dual RTX 4090, 128 GB RAM, $7,631€7,330. price unverified It runs gpt-oss-20b the same way: the extra memory only helps with models too big for the cards.
The cheapest graphics card on our list that also runs it (it still needs the rest of a PC): Radeon RX 9060 XT 16GB, $522€564, new (cheapest in-stock board on GPU PRIX's German board list).
EU shops · In the US? Switch the currency to USD.US shops · In Europe? Switch the currency to EUR.
The cheapest complete machine that runs it: Mac mini M6 32GB, $1,416€1,530. price unverified
gpt-oss-20b on other graphics cards
Runs well8
The whole model fits in the graphics memory.
Doesn't fit1
Not enough graphics memory: it needs about 13.1 GB.
- RTX 3060 12GBhas 12 GB
More about the model itself, what it is good at and its licence: gpt-oss-20b.
The numbers behind this answer
A model comes in several sizes. Q4 is the standard one most people use; the bigger ones answer a little better but need more memory. Each row adds up the model file, the memory a conversation takes, and some working space, and compares the total with what is free on this machine.
Swipe the table sideways to see every column.
| Quality | Conversation | Result | Model file | Conversation memory | Working space | Total needed | Free memory |
|---|---|---|---|---|---|---|---|
| Q4 · standard (smallest that keeps quality) | ~12 pages8,192 tokens | Runs | 12.1 GBmeasured file | 0.2 GB | 0.8 GB | 13.1 GB | 46.8 GB |
| Q5 · a bit sharper, a bit bigger | ~12 pages8,192 tokens | Runs | 13.8 GB | 0.2 GB | 0.8 GB | 14.8 GB | 46.8 GB |
| Q8 · near full quality, almost twice Q4 | ~12 pages8,192 tokens | Runs | 13.8 GB | 0.2 GB | 0.8 GB | 14.8 GB | 46.8 GB |
| FP16 · full quality, over three times Q4 | ~12 pages8,192 tokens | Runs | 13.8 GBmeasured file | 0.2 GB | 0.8 GB | 14.8 GB | 46.8 GB |
| Q4 · standard, longer conversation | ~49 pages32,768 tokens | Runs | 12.1 GBmeasured file | 0.8 GB | 0.8 GB | 13.7 GB | 46.8 GB |
speed: not estimated for MoE yet. This model only uses part of itself for each word (a mixture of experts), and our speed estimate does not handle that yet.
Questions
- Can I run gpt-oss-20b on a Dual RTX 4090?
- Yes. gpt-oss-20b runs on a Dual RTX 4090: the whole model fits in its graphics memory.
- How much memory does gpt-oss-20b need?
- About 13.1 GB at the standard quality (Q4) for a conversation of up to about 12 pages of text (8,192 tokens), by our estimate: 12.1 GB for the model file (measured), 0.2 GB to hold the conversation and 0.8 GB of working space.
- How fast is gpt-oss-20b on a Dual RTX 4090?
- We don't give a speed for this model yet. This model only uses part of itself for each word (a mixture of experts), and our speed estimate does not handle that yet.
Speeds and memory are our estimate from the hardware specs, not a measured test. Prices are dated and may change. How we calculate