Can I Run GPT-OSS 120B on AMD Radeon RX 7900 XTX?
Written by Jakub Rusinowski · Last updated July 12, 2026
No. GPT-OSS 120B needs 71.9 GB at 8K context (70.5 GB weights + 1.4 GB KV cache/overhead) at Q4_K_M and the AMD Radeon RX 7900 XTX has only 24 GB. No quantization we publish closes a gap that size.
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The numbers
| Model | GPT-OSS 120B |
| Parameters | 120B |
| Quantization | Q4_K_M |
| VRAM needed (8K context) | 71.9 GB |
| AMD Radeon RX 7900 XTX VRAM | 24 GB |
| Verdict | Does not fit |
GPT-OSS 120B on the AMD Radeon RX 7900 XTX: VRAM by quantization
| Quant | VRAM needed | Fits 24 GB? | Max context | Whole PC |
|---|---|---|---|---|
| F16 | 235 GB | ✗ No | — | — |
| Q8_0 | 125.5 GB | ✗ No | — | — |
| Q6_K | 97.2 GB | ✗ No | — | — |
| Q5_K_M | 84.2 GB | ✗ No | — | — |
| Q4_K_M | 71.9 GB | ✗ No | — | — |
| Q3_K_M | 51.2 GB | ✗ No | — | — |
| Q2_K | 39.8 GB | ✗ No | — | — |
Assumes an 8K-token context with an f16 KV cache. A longer window needs more; a quantized KV cache needs less. “Max context” is the largest window that still fits in 24 GB. Figures are estimates from parameter count, quantization and memory bandwidth — the analyzer lets you tune KV-cache quant and context.
Context costs VRAM too. At Q4_K_M on the AMD Radeon RX 7900 XTX: 8K 71.9 GB ✗ · 32K 73.7 GB ✗ · 128K 81 GB ✗. Past 8K it no longer fits 24 GB — a q8_0 KV cache buys roughly half of that back, which the calculator will price for you.
What to do next
Either step down to a smaller size in this family, or move to a NVIDIA RTX PRO 5000 Blackwell (72 GB) (72 GB), the card with the least memory we track that holds it.
No compatible GPU? GPT-OSS 120B on 96 GB of system RAM, CPU only: runs, but it is tight.
GPT-OSS 120B needs ~72 GB but this GPU has 24 GB. Rent a A100 (80 GB)-class GPU by the hour instead of buying one:
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Cloud rates verified 2026-07 — estimates, and marketplace prices vary. Buying price is GPU MSRP only, not a full PC.
Other GPT-OSS sizes on the AMD Radeon RX 7900 XTX
- GPT-OSS 20B — runs (12.3 GB)
GPT-OSS 120B on nearby hardware
- AMD Radeon RX 7900 XT (20 GB) — does not fit
- NVIDIA A100 80GB (PCIe) (80 GB) — runs
All GPT-OSS sizes on the AMD Radeon RX 7900 XTX | GPT-OSS 120B model page | AMD Radeon RX 7900 XTX GPU page | VRAM calculator | Check your hardware