Can I run gpt-oss-120b on a Dual RTX 4090?
Only slowly: gpt-oss-120b is too big for the graphics memory of a Dual RTX 4090, so part of it runs from normal 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-120b on every card
How much memory it needs
That is more than this machine has free, so the rest spills into normal memory.
What runs gpt-oss-120b fully in graphics memory
The cheapest machine on our list that holds the whole model in its graphics memory:
Mac Studio M4 Max 128GB$3,683€3,290price unverified
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Price details
$3,683€3,290
How we priced this
Not checked against a shop listing (price unverified). Price from 16 Oct 2026.
Used-market euro amount from an earlier check of ours. Used prices cannot be checked on the Apple Store.
Prices excl. shipping. Euro prices incl. VAT. Dollar prices are converted from our euro prices without EU VAT, before US sales tax.
See our picks for gpt-oss-120b in Find hardware. Add your budget to see cheaper machines.
For comparison, a Dual RTX 4090 with 64 GB of normal memory (RAM) costs about $5,910€5,470. price unverified With 128 GB it gives the same answer and costs about $7,631€7,330. price unverified Machine details: Dual RTX 4090, 64 GB RAM, Dual RTX 4090, 128 GB RAM.
gpt-oss-120b on other graphics cards
Runs slowly2
Part of the model spills into normal memory, which is much slower.
Doesn't fit7
Not enough graphics memory: it needs about 64.5 GB.
- RTX 3060 12GBhas 12 GB
- RTX 4060 Ti 16GBhas 16 GB
- RTX 3090has 24 GB
- RTX 4090has 24 GB
- RTX 5080has 16 GB
- RTX 5090has 32 GB
- RX 7900 XTXhas 24 GB
More about the model itself, what it is good at and its licence: gpt-oss-120b.
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 slowly | 63.4 GBmeasured file | 0.3 GB | 0.8 GB | 64.5 GB | 46.8 GB |
| Q5 · a bit sharper, a bit bigger | ~12 pages8,192 tokens | Runs slowly | 65.4 GB | 0.3 GB | 0.8 GB | 66.5 GB | 46.8 GB |
| Q8 · near full quality, almost twice Q4 | ~12 pages8,192 tokens | Runs slowly | 65.4 GB | 0.3 GB | 0.8 GB | 66.5 GB | 46.8 GB |
| FP16 · full quality, over three times Q4 | ~12 pages8,192 tokens | Runs slowly | 65.4 GBmeasured file | 0.3 GB | 0.8 GB | 66.5 GB | 46.8 GB |
| Q4 · standard, longer conversation | ~49 pages32,768 tokens | Runs slowly | 63.4 GBmeasured file | 1.2 GB | 0.8 GB | 65.4 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-120b on a Dual RTX 4090?
- Only slowly: gpt-oss-120b is too big for the graphics memory of a Dual RTX 4090, so part of it runs from normal memory.
- How much memory does gpt-oss-120b need?
- About 64.5 GB at the standard quality (Q4) for a conversation of up to about 12 pages of text (8,192 tokens), by our estimate: 63.4 GB for the model file (measured), 0.3 GB to hold the conversation and 0.8 GB of working space.
- How fast is gpt-oss-120b 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