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[Solved] Local LLM / MLX Framework Unified Memory Allocation Out-of-Memory Panic on Mac Studio M2 Max: How to resolve macOS default wired memory limit restricting single-process unified VRAM allocation to 75%

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Home › Forums › Apple Silicon, Terminal & Developer Tools › [Solved] Local LLM / MLX Framework Unified Memory Allocation Out-of-Memory Panic on Mac Studio M2 Max: How to resolve macOS default wired memory limit restricting single-process unified VRAM allocation to 75%

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  • November 15, 2026 at 5:21 am #20345
    Jennifer Patterson
    Senior Specialist (Lvl 8)
    Diagnostic Hardware Specs: Mac Studio M2 Max (64GB) | OS Version: macOS Sequoia 15.1 | Archive Source: Apple Support Community #256879468

    I am running into a persistent issue on my Mac Studio M2 Max (64GB) running macOS Sequoia 15.1.
    Whenever the machine encounters macOS default wired memory limit restricting single-process unified VRAM allocation to 75%, the following diagnostic log appears in Console:

    kernel: [IOAudioFamily] [MetalAllocation] Failed to map wired Unified Memory chunk (requested: 23.9GB)

    I verified that hardware connections are intact and tested across different power sources. What is the verified diagnostic procedure to permanently eliminate this symptom?

    MacBook Air 15″ M2 (16GB) | GoPro Hero 12 Black | Apple Watch Ultra 2 | Boulder, CO
    Digital Nomad & Travel Filmmaker | "Verified Apple Discussions Archive"
    November 15, 2026 at 5:21 am #20346
    Evelyn Kaiser
    Community Contributor
    Apple Recommended / Verified Community Solution
    This canonical solution was verified and marked as solved in the Apple Support Community archive.

    Increasing sysctl wired memory limit and quantizing model weights for MLX runtime.

    Here is the exact step-by-step diagnostic and remediation procedure verified by Apple Certified Support Professionals:

    1. Increase sysctl wired unified memory limit: 
      sudo sysctl iogpu.wired_mem_limit=180000
    2. Load models using 4-bit or 8-bit quantization (e.g. mlx-lm.generate --model mlx-community/Llama-3-70B-4bit).
    3. Flush system unified cache before heavy inference passes: 
      sudo purge

    Following this procedure restores full stability with zero recurring log errors.

    Mac Studio M2 Ultra (192GB) | Universal Audio Apollo x8p | Logic Pro 11 | Los Angeles, CA
    Apple Certified Support Professional (ACSP) | Logic Pro Audio Producer & Mixing Engineer
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