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Models / Muse Spark Open 816B
Muse Spark Open 816B VRAM Requirements & GPU Pairing
Muse Spark Open (released October 15, 2026) is Meta's most capable open-weight model to date: a pure MoE with 816B total / 42B active parameters — all 62 layers run 256 experts with 8 active per token, no shared expert, experts holding ~799B of the 816B; 128 Q heads / 16 KV heads / headDim 64; a native 1M-token context; and native multimodality (text/image/video/audio in, text out, via a 1.8B perception encoder). The license is the Muse Model License (attribution "Built with Muse Spark Open"; MaaS revenue above $20M requires a separate agreement) — not Apache. Attention runs on a 4-layer cycle of three 2048-token sliding-window layers plus one full-attention layer; measured KV is ~250KB/token in bf16 (~266GB at the full 1M context). Our standard formula assumes full attention everywhere and overestimates long-context KV by ~4×, so verdicts are conservative.
Q4_K_M @8K totals ~503GB: no single GPU and no single 512GB Mac Studio (~384GB usable) can hold it, and Meta's own consumer path is exactly two 512GB M5 Ultra Studios over Thunderbolt 5 running MLX (measured ~16-25 tok/s; our multi-machine theoretical figure of ~59 tok/s ignores clustering interconnect losses and is optimistic). A single machine only fits at Q2_K level (~327GB, tight) — matching real-world 344GB 3-bit oQ3e builds: usable, with quality loss, and Unsloth recommends at least IQ2_S for agentic work. For most users the realistic route is a hosted API (Together at $1.25/$4.25 per 1M tokens). It is the largest model we list — a reference point beyond the consumer ceiling.
Architecture Specs
| Total parameters | 816B |
| Active parameters(MoE: VRAM follows total params, speed follows active params) | 42B |
| Layers | 62 |
| KV heads | 16 |
| Head dim | 64 |
| Native context | 1024K |
| License | muse-model-license |
| KV bytes per token (fp16) | 248.0 KB |
Hybrid-attention note: only 1 in 4 layers is full attention; the other three use 2048-token sliding windows. The table computes KV with the standard full-attention formula — real long-context usage is roughly 1/4 of the shown value (official figure: ~266GB at the full 1M context), so verdicts are conservative.
VRAM by Quant Tier (@8K context, fp16 KV)
| Quant | Weights | Total (incl. 1.5GB runtime overhead) |
|---|---|---|
| Q8_0 | 868.0 GB | 871.6 GB |
| Q6_K | 670.1 GB | 673.7 GB |
| Q4_K_M | 499.8 GB | 503.4 GB |
| Q3_K_M | 408.0 GB | 411.6 GB |
| Q2_K | 323.3 GB | 326.9 GB |
KV cache and runtime overhead do not change across quants; longer contexts grow the KV part linearly — adjust context length in the GPU checker tool.
GPU Verdict Matrix (Q4_K_M @8K)
| GPU | Usable VRAM | Verdict | Recommended quant | Theoretical speed | |
|---|---|---|---|---|---|
| RTX 3060 12GB | 12.0 GB | Not feasible | — | — | Try it → |
| RTX 3090 | 24.0 GB | Not feasible | — | — | Try it → |
| RTX 4070 Ti Super | 16.0 GB | Not feasible | — | — | Try it → |
| RTX 4090 | 24.0 GB | Not feasible | — | — | Try it → |
| RTX 5090 | 32.0 GB | Not feasible | — | — | Try it → |
| RTX A6000 | 48.0 GB | Not feasible | — | — | Try it → |
| A100 80GB | 80.0 GB | Not feasible | — | — | Try it → |
| H100 80GB | 80.0 GB | Not feasible | — | — | Try it → |
| RX 7900 XTX | 24.0 GB | Not feasible | — | — | Try it → |
| Mac mini M4 Pro (48GB) | 36.0 GB | Not feasible | — | — | Try it → |
| Mac Studio M4 Max (64GB) | 48.0 GB | Not feasible | — | — | Try it → |
| Mac Studio M3 Ultra (96GB) | 72.0 GB | Not feasible | — | — | Try it → |
| Mac Studio M5 Ultra (96GB) | 72.0 GB | Not feasible | — | — | Try it → |
| Mac Studio M5 Ultra (512GB) | 384.0 GB | Not feasible | Q2_K | ≈54 tok/s | Try it → |
Theoretical speed = bandwidth × 0.75 ÷ per-token weight bytes (active params for MoE); real-world results vary with framework/driver/CPU, ±30%.
FAQ
- How much VRAM does Muse Spark Open need?
- ~503GB at Q4_K_M @8K — infeasible on any single card or a single 512GB Mac Studio. Two 512GB M5 Ultra Studios (~768GB usable combined) are comfortable; a single 512GB machine only fits Q2_K-level quants (~327GB, tight). Full BF16 is ~1.5TB — datacenter territory.
- Can one 512GB Mac Studio run Muse Spark Open?
- Only with aggressive quantization: ~327GB at Q2_K by our formula (tight), and real-world 344GB 3-bit oQ3e builds have been shown working at ~21 tok/s. The official sweet spot is the dual-Studio MLX setup. Below 2-bit is not advisable for agentic use.
- Muse Spark Open or GLM-5.3-Flash?
- GLM-5.3-Flash (321B, MIT) needs less than half the capacity and is reachable at 3-bit on a 256GB Mac; Muse Spark Open has the higher ceiling, native multimodality and 1M context, but its only realistic consumer paths are a dual-512GB Studio cluster or a hosted API. Pick GLM-5.3-Flash for budget, Muse for ceiling and multimodality.
Related guides
- MoE Model Hardware Requirements: Total vs Active Parameters
- The VRAM Cost of Long Context (and How to Right-Size It)
- Multi-GPU Setup for Local LLMs: NVLink, PCIe & Layer Splitting
Try Muse Spark Open 816B in the GPU compatibility checker →
Data verified 2026-11-01