Llama 3.1 405B needs ~284.4 GB VRAM. AMD Instinct MI350X 288GB has 288.0 GB. With Q4_K_M quantization, expect ~26 tok/s.
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
Fit status
Runs with offload
Decode
25.9 tok/s
TTFT
7488 ms
Safe context
23K
Memory
284.4 GB / 288.0 GB
This setup is broadly balanced for this model.
Very little memory headroom
You can run the model, but there is not much room left for longer context, bigger batches, extra apps, or future model updates.
Buy headroom, not only minimum fit
A slightly larger memory tier gives you safer context growth and makes the recommendation more future-proof.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | A | Runs with offload | 25.9 tok/s | 4084 ms | 23K |
| Coding | A | Runs with offload | 25.9 tok/s | 7488 ms | 23K |
| Agentic Coding | A | Runs with offload (needs ~3.5 GB host RAM) | 18.8 tok/s | 14964 ms | 23K |
| Reasoning | A | Runs with offload | 25.9 tok/s | 8849 ms | 23K |
| RAG | A | Runs with offload (needs ~3.5 GB host RAM) | 18.8 tok/s | 18705 ms | 23K |
Inference speed
Estimated decode speed (tokens/sec) for Llama 3.1 405B at Q4_K_M across popular GPUs and Apple Silicon, including multi-GPU rigs, using the fastest local runtime per device. Fastest is RTX 5090 32GB at ~2 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? |
|---|---|---|---|---|
| 32 GB | Q4_K_M | 2.0 | Too big | |
| 24 GB | Q4_K_M | 2.0 | Too big | |
| 16 GB | Q4_K_M | 2.0 | Too big | |
| 24 GB | Q4_K_M | 2.0 | Too big | |
| 12 GB | Q4_K_M | 2.0 | Too big | |
| 12 GB | Q4_K_M | 2.0 | Too big | |
| 8 GB | Q4_K_M | 2.0 | Too big | |
RX 7900 XTX 24GB | 24 GB | Q4_K_M | 2.0 | Too big |
MacBook Pro M4 Max 128GB | 128 GB | Q4_K_M | 2.0 | Too big |
Mac Studio M3 Ultra 256GB | 256 GB | Q4_K_M | 2.0 | Too big |
Mac Studio M2 Ultra 128GB | 128 GB | Q4_K_M | 2.0 | Too big |
Mac Studio M1 Ultra 128GB | 128 GB | Q4_K_M | 2.0 | Too big |
MacBook Pro M4 Max 64GB | 64 GB | Q4_K_M | 2.0 | Too big |
MacBook Pro M3 Max 64GB | 64 GB | Q4_K_M | 2.0 | Too big |
MacBook Pro M1 Max 64GB | 64 GB | Q4_K_M | 2.0 | Too big |
MacBook Pro M4 Pro 48GB | 48 GB | Q4_K_M | 2.0 | Too big |
| 48 GB | Q4_K_M | 2.0 | Too big | |
| 48 GB | Q4_K_M | 2.0 | Too big | |
2× RX 7900 XTX 24GB | 48 GB | Q4_K_M | 2.0 | Too big |
| 48 GB | Q4_K_M | 2.0 | 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 Llama 3.1 405B (405B params) fits at each quantization level on AMD Instinct MI350X 288GB (288.0 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 158.0 GB | Low | A82 |
Q3_K_S | 3 | 198.5 GB | Low | A82 |
NVFP4Best for your GPU | 4 | 226.8 GB | Medium | A82 |
Q4_K_M | 4 | 247.1 GB | Medium | F0 |
Q5_K_M | 5 | 291.6 GB | High | F0 |
Q6_K | 6 | 332.1 GB | High | F0 |
Q8_0 | 8 | 433.4 GB | Very High | F0 |
F16 | 16 | 830.2 GB | Maximum | F0 |
Copy-paste commands to run Llama 3.1 405B on your machine.
Run
ollama run llama3.1:405bYour hardware
| Model | Params | Grade | Decode | Capabilities |
|---|---|---|---|---|
| 480B | A | 35.3 tok/s |
Yes, AMD Instinct MI350X 288GB can run Llama 3.1 405B with a A grade (Runs with offload). Expected decode speed: 25.9 tok/s.
Llama 3.1 405B (405B parameters) requires approximately 284.4 GB of memory with Q4_K_M quantization.
The recommended quantization for Llama 3.1 405B is Q4_K_M, which balances quality and memory efficiency.
On AMD Instinct MI350X 288GB, Llama 3.1 405B achieves approximately 25.9 tokens per second decode speed with a time-to-first-token of 7488ms using Q4_K_M quantization.
For coding workloads, Llama 3.1 405B on AMD Instinct MI350X 288GB receives a A grade with 25.9 tok/s and 23K context.
On AMD Instinct MI350X 288GB, Llama 3.1 405B can safely use up to 23K tokens of context. The model's official context limit is 131K, but available memory constrains the safe maximum.
Buy headroom, not only minimum fit. A slightly larger memory tier gives you safer context growth and makes the recommendation more future-proof.
Paste this snippet into any page to show a live fit card.
<iframe src="https://willitrunai.com/embed/llama-3.1-405b-on-instinct-mi350x-288gb" width="400" height="180" frameborder="0" style="border:none;border-radius:12px;overflow:hidden;" title="Will It Run AI — fit result"></iframe>
Preview: