Mixtral 8x7B needs ~33.1 GB but RX 6950 XT 16GB only has 16.0 GB. Try a smaller quantization or lighter model.
Operating mode
Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.
Current mode
Balanced
Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.
Select quantization to explore
17.1 GB over capacity — needs offload or smaller quantization
Fit status
Too heavy
Decode
3.9 tok/s
TTFT
49692 ms
Safe context
4K
Memory
33.1 GB / 16.0 GB
Offload
50%
Usable VRAM is the main blocker for this model.
Not enough usable memory
The model needs 33.1 GB, but this setup only exposes 16.0 GB of usable VRAM.
Add more VRAM headroom
The first useful upgrade is more dedicated VRAM so you can fit the model without shrinking context or dropping to a much lower quant.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | F | Too heavy | 4.1 tok/s | 25450 ms | 4K |
| Coding | F | Too heavy | 3.9 tok/s | 49692 ms | 4K |
| Agentic Coding | F | Too heavy | 3.6 tok/s | 78123 ms | 4K |
| Reasoning | F | Too heavy | 3.9 tok/s | 58727 ms | 4K |
| RAG | F | Too heavy | 3.6 tok/s | 97654 ms | 4K |
Inference speed
Estimated decode speed (tokens/sec) for Mixtral 8x7B at Q4_K_M across popular GPUs and Apple Silicon, including multi-GPU rigs, using the fastest local runtime per device. Fastest is 2× RX 7900 XTX 24GB at ~85 tok/s. Speed is memory-bandwidth bound, so cards that fit the whole model in VRAM run far faster than ones that offload to system RAM.
| GPU / Mac | Memory | Quant | Speed (tok/s) | Fits? |
|---|---|---|---|---|
2× RX 7900 XTX 24GB | 48 GB | Q4_K_M | 84.5 | Fits |
 2× RTX 4090 24GB | 48 GB | Q4_K_M | 77.1 | Fits |
| 2× RTX 3090 24GB | 48 GB | Q4_K_M | 66.0 | Fits |
| 4× RTX 3060 12GB | 48 GB | Q4_K_M | 58.1 | Fits |
| RTX 5090 32GB | 32 GB | Q4_K_M | 54.9 | Heavy offload |
Mac Studio M3 Ultra 256GB | 256 GB | Q4_K_M | 40.1 | Fits |
Mac Studio M2 Ultra 128GB | 128 GB | Q4_K_M | 33.4 | Fits |
Mac Studio M1 Ultra 128GB | 128 GB | Q4_K_M | 31.6 | Fits |
MacBook Pro M4 Max 128GB | 128 GB | Q4_K_M | 24.7 | Fits |
MacBook Pro M4 Max 64GB | 64 GB | Q4_K_M | 24.7 | Tight |
| RTX 4090 24GB | 24 GB | Q4_K_M | 19.6 | Too big |
RX 7900 XTX 24GB | 24 GB | Q4_K_M | 18.0 | Too big |
MacBook Pro M3 Max 64GB | 64 GB | Q4_K_M | 17.3 | Tight |
| RTX 3090 24GB | 24 GB | Q4_K_M | 16.7 | Too big |
MacBook Pro M1 Max 64GB | 64 GB | Q4_K_M | 15.8 | Tight |
MacBook Pro M4 Pro 48GB | 48 GB | Q4_K_M | 13.6 | Offloads |
| RTX 4080 Super 16GB | 16 GB | Q4_K_M | 7.0 | Too big |
| RTX 4070 12GB | 12 GB | Q4_K_M | 4.1 | Too big |
| RTX 3060 12GB | 12 GB | Q4_K_M | 2.6 | Too big |
| RTX 4060 8GB | 8 GB | Q4_K_M | 2.1 | Too big |
Estimates for single-stream decoding at Q4_K_M; real tokens/sec varies with prompt length, context, batch size, and runtime build. Prompt processing (prefill) is faster than the decode figures shown here.
How Mixtral 8x7B (47B params) fits at each quantization level on RX 6950 XT 16GB (16.0 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 18.3 GB | Low | F0 |
Q3_K_S | 3 | 23.0 GB | Low | F0 |
NVFP4 | 4 | 26.3 GB | Medium | F0 |
Q4_K_M | 4 | 28.7 GB | Medium | F0 |
Q5_K_M | 5 | 33.8 GB | High | F0 |
Q6_K | 6 | 38.5 GB | High | F0 |
Q8_0 | 8 | 50.3 GB | Very High | F0 |
F16 | 16 | 96.4 GB | Maximum | F0 |
Upgrade options
Makes the model fit on the accelerator instead of staying completely out of reach.
Raises estimated decode speed by about 351%.
~$1,899 MSRP
Makes the model fit on the accelerator instead of staying completely out of reach.
Raises estimated decode speed by about 233%.
~$2,249 MSRP
Makes the model fit on the accelerator instead of staying completely out of reach.
Removes host-memory offload, which is usually the single biggest latency and throughput win.
~$3,999 MSRP
No, Mixtral 8x7B requires more memory than RX 6950 XT 16GB provides.
Mixtral 8x7B (47B parameters) requires approximately 33.1 GB of memory with Q4_K_M quantization.
The recommended quantization for Mixtral 8x7B is Q4_K_M, which balances quality and memory efficiency.
On RX 6950 XT 16GB, Mixtral 8x7B achieves approximately 3.9 tokens per second decode speed with a time-to-first-token of 49692ms using Q4_K_M quantization.
For coding workloads, Mixtral 8x7B on RX 6950 XT 16GB receives a F grade with 3.9 tok/s and 4K context.
On RX 6950 XT 16GB, Mixtral 8x7B can safely use up to 4K tokens of context. The model's official context limit is 33K, but available memory constrains the safe maximum.
Add more VRAM headroom. The first useful upgrade is more dedicated VRAM so you can fit the model without shrinking context or dropping to a much lower quant.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/mixtral-8x7b-on-rx-6950-xt-16gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>
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