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Mac Studio M5 Ultra (512GB) for Local LLMs: What It Runs and How Fast
The Mac Studio M5 Ultra 512GB (on sale October 28, 2026) is Apple's single-machine memory ceiling: 512GB of unified memory at 1.2TB/s, i.e. ~384GB usable at the 75% rule. The price is not gentle — 512GB requires the high-end chip config (36-core CPU / 80-core GPU, from $6,799) plus a $15,500 memory upgrade, for a $22,299 minimum; the 512GB + 16TB flagship is $29,799. In capacity terms one box equals five 96GB Ultras: GLM-5.3-Flash Q4 (~199GB), Qwen3.8-Flash-Next Q8 (~194GB) and gpt-oss-120b Q8 (~126GB) all fit comfortably, and even DeepSeek-R1 at Q3_K_M (~337GB) squeezes in.
It still cannot hold the largest model we list: Muse Spark Open at Q4_K_M is ~503GB — infeasible on one machine, comfortable on two (~768GB usable) — which is exactly Meta's official dual-Studio MLX demo (measured ~16-25 tok/s). Selection logic: working sets ≤72GB take the 96GB ($5,499); 85-192GB the 256GB; 192-380GB (GLM-5.3-Flash Q6_K/Q8, R1 Q3 tier) is where the 512GB earns its premium; anything beyond 384GB usable means a Thunderbolt 5 dual-machine pool, not a bigger box. Memory is soldered — choose the tier at purchase. tdpW is a whole-system estimate.
Specs
| Nominal VRAM | 512 GB |
| Usable VRAM (for models) | 384.0 GB |
| Memory bandwidth | 1200 GB/s |
| Type | Unified memory |
| Release year | 2026 |
| MSRP | $22,299 |
| TDP | 140 W |
Apple unified memory is counted at 75% usable for models (the rest serves the system/display).
Value Metrics
Based on MSRP (no used price yet); used prices are market estimates, see commentary for volatility.
Model Verdict Matrix (Q4_K_M @8K)
| Model | VRAM needed | Verdict | Recommended quant | Theoretical speed | |
|---|---|---|---|---|---|
| Llama 3.2 3B | 4.4 GB | Comfortable | FP16 | ≈140 tok/s | Try it → |
| Llama 3.1 8B | 7.5 GB | Comfortable | FP16 | ≈56 tok/s | Try it → |
| Qwen3 8B | 7.7 GB | Comfortable | FP16 | ≈55 tok/s | Try it → |
| Phi-4 14B | 12.2 GB | Comfortable | FP16 | ≈31 tok/s | Try it → |
| Mistral Small 3.2 24B | 17.5 GB | Comfortable | FP16 | ≈19 tok/s | Try it → |
| Gemma 3 27B | 22.4 GB | Comfortable | FP16 | ≈16 tok/s | Try it → |
| Qwen3.8 27B | 20.7 GB | Comfortable | FP16 | ≈16 tok/s | Try it → |
| Muse Glimmer 30B | 20.1 GB | Comfortable | FP16 | ≈15 tok/s | Try it → |
| Qwen3 30B-A3B | 21.0 GB | Comfortable | FP16 | ≈136 tok/s | Try it → |
| Qwen3 32B | 23.7 GB | Comfortable | FP16 | ≈14 tok/s | Try it → |
| gpt-oss-20b | 14.7 GB | Comfortable | FP16 | ≈125 tok/s | Try it → |
| Llama 3.3 70B | 47.4 GB | Comfortable | FP16 | ≈6 tok/s | Try it → |
| gpt-oss-120b | 73.6 GB | Comfortable | FP16 | ≈88 tok/s | Try it → |
| Qwen3.8 Flash-Next | 112.6 GB | Comfortable | FP16 | ≈75 tok/s | Try it → |
| GLM-5.3-Flash | 198.7 GB | Comfortable | Q8_0 | ≈47 tok/s | Try it → |
| DeepSeek-R1 671B | 413.1 GB | Needs multi-GPU | Q3_K_M | ≈49 tok/s | Try it → |
| Muse Spark Open 816B | 503.4 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
- What can the Mac Studio M5 Ultra 512GB run?
- With ~384GB usable, it fits all 17 models we list except Muse Spark Open at Q4 (~503GB): GLM-5.3-Flash Q4 (~199GB) is comfortable, DeepSeek-R1 Q3_K_M (~337GB) is tight, Qwen3.8-Flash-Next Q8 is comfortable. Muse Spark Open needs Q2_K-level quants on one machine (~327GB, tight) or the dual-Studio MLX setup.
- What does the 512GB version cost at minimum?
- $22,299: the high-end chip config at $6,799 plus the $15,500 512GB memory upgrade (with 1TB storage); the 512GB + 16TB flagship is $29,799 (Apple Store, 2026-10-28).
- One 512GB Studio or two smaller-memory Studios?
- Two 96GB Ultras cost ~$11K but offer only ~144GB usable — a different capacity class entirely. Two 256GB units match ~384GB usable for less money but add clustering overhead and ops. Pick the single 512GB for simplicity and lossless 1.2TB/s bandwidth; pick a duo to spread cost if you accept Thunderbolt clustering losses.
Related guides
- Mac vs GPU for LLM Inference: Unified Memory Explained
- Multi-GPU Setup for Local LLMs: NVLink, PCIe & Layer Splitting
- Why Memory Bandwidth Determines LLM Inference Speed
Try Mac Studio M5 Ultra (512GB) in the GPU compatibility checker →
Data verified 2026-11-01