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Run LLM Locally

Mixtral 8x7B Instruct on the RX 7900 XTX

Mixtral 8x7B Instruct at Q4_K_M needs about 27.6 GB, more than the 24 GB of the RX 7900 XTX: part of the model runs from system RAM, which slows generation. At Q3_K_M it fits entirely.

Mixtral 8x7B Instruct

Q4_K_M · 8K context

CPU/GPU offload

The model needs about 27.6 GB but only 23.3 GB of VRAM is usable: 4.3 GB must be loaded into system RAM. It runs, 84% on the GPU, but more slowly.

Your hardware
RX 7900 XTX 24 GB · 64 GB RAM
Estimated memory
~27.6 GB estimate
VRAM (usable memory)
23.3 GB
GPU only
No
CPU/GPU offload
Required (4.3 GB)
Generation speed
12–23 tok/s estimate
Largest context in fast memory
None
Confidence: low

Based on: memory bandwidth (960 GB/s) and model size · system RAM bandwidth (~51 GB/s)

Memory breakdown

~27.6 GB (26.8 GB–28.4 GB) needed · estimate

4.3 GB must be offloaded to system RAM

  • Model weights24.6 GB
  • KV cache1 GB
  • Runtime overhead0.6 GB
  • Safety margin1.3 GB
Assumptions: context 8K tokens · KV cache f16 · llama.cpp (ROCm) · flash attention on · weights = real file size

EstimateData updated 24 days agoSource: Run LLM Locally engine, Hugging Face config.json + model card

What makes this estimate less reliable

  • no benchmark for this hardware and model yet
  • split CPU/GPU runs vary a lot with the CPU and PCIe link
  • system RAM speed unknown (dual-channel DDR4-3200 assumed)
  • mixture-of-experts: speed depends on expert routing

Other quantizations on the RX 7900 XTX

Mixtral 8x7B Instruct on RX 7900 XTX + 64 GB RAM · 8K context
Mixtral 8x7B Instruct Q8_08K~50.2 GB · 2.5–5 tok/s estimatePossible but slow
Mixtral 8x7B Instruct Q6_K8K~39.2 GB · 4–7.5 tok/s estimateCPU/GPU offload
Mixtral 8x7B Instruct Q5_K_M8K~33.2 GB · 6–12 tok/s estimateCPU/GPU offload
Mixtral 8x7B Instruct Q4_K_M8K~27.6 GB · 12–23 tok/s estimateCPU/GPU offload
Mixtral 8x7B Instruct IQ4_XS8K~27.2 GB · 13–25 tok/s estimateCPU/GPU offload
Mixtral 8x7B Instruct Q3_K_M8K~21.6 GB · 59–93 tok/s estimateCompatible

Alternatives

Hardware that runs Mixtral 8x7B Instruct Q4_K_M entirely in memory

Prices and links follow the market you choose.

GeForce RTX 5090

NVIDIA

CompatibleRuns Mixtral 8x7B Instruct Q4_K_M entirely in memory

Price not available

Availability unknown

View on amazon.com

Affiliate link

Radeon PRO W7900

AMD

ExcellentRuns Mixtral 8x7B Instruct Q4_K_M entirely in memory

Price not available

Availability unknown

View on amazon.com

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MacBook Pro 14 M3 Max

Apple Silicon

ExcellentRuns Mixtral 8x7B Instruct Q4_K_M entirely in memory

Price not available

Availability unknown

View on amazon.com

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AMD Ryzen AI Max+ 395

Unified memory PC

ExcellentRuns Mixtral 8x7B Instruct Q4_K_M entirely in memory

Price not available

Availability unknown

View on amazon.com

Affiliate link

No current offer imported for this market: the link opens a marketplace search.

Frequently asked questions

Can the RX 7900 XTX run Mixtral 8x7B Instruct?
The model needs about 27.6 GB but only 23.3 GB of VRAM is usable: 4.3 GB must be loaded into system RAM. It runs, 84% on the GPU, but more slowly.
Which quantization should I use on the RX 7900 XTX?
Q3_K_M is the highest-precision quantization that fits entirely in VRAM at 8K context. ~21.6 GB / 23.3 GB.
What is the largest context on the RX 7900 XTX?
At Q4_K_M, the model does not fit entirely in VRAM even at a short context.
How fast is Mixtral 8x7B Instruct (RX 7900 XTX)?
We estimate 12–23 tok/s (estimate, confidence low). Based on: memory bandwidth (960 GB/s) and model size, system RAM bandwidth (~51 GB/s).