Can the Mac 128 GB run MiniMax H3 (33B)?
Download 16-bit (66.3 GB). With the model's working memory it needs about 72.1 GB, leaving 43.3 GB spare on 115.4 GB. Quality: the original weights.
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | minimax_h3_fl2va_bf16.safetensors 16-bit · Comfy-Org/MiniMax-H3 | models/diffusion_models | 66.3 GB | Download → |
| Text encoder | qwen3vl_32b_minimax_h3_bf16.safetensors Qwen3-VL 32B BF16 · Comfy-Org/MiniMax-H3 | models/text_encoders | 51.5 GB | Download → |
| VAE | minimax_h3_video_vae_fp16.safetensors MiniMax H3 video VAE FP16 · Comfy-Org/MiniMax-H3 | models/vae | 5.2 GB | Download → |
| Also needed | minimax_h3_audio_vae_fp32.safetensors MiniMax H3 audio VAE FP32 · Comfy-Org/MiniMax-H3 | models/vae | 0.6 GB | Download → |
| Total download · keep about the same free on disk | 123.6 GB | |||
On a Mac, FP8 text encoders do not load, so a 16-bit one is listed. Sizes read from Hugging Face (2026-09-25). “Download” links start the file directly; the file name links are the same files the official ComfyUI workflows use.
Shared memory: about 129.6 GB of your 128 GB. On this machine the model, the text encoder, the VAE and the operating system all use the same memory. That is about 1.6 GB more than there is. It still runs: while the model works, the system compresses or swaps the idle text encoder, so loading and changing the prompt get slower. A smaller file or text encoder avoids that. calculated
02Every MiniMax H3 file on 115.4 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit ← SAFETENSORS · Comfy-Org | 66.3 GB | 72.1 GB | fits · 43.3 GB spare | the original weights | Hugging Face → |
| Q8_0 GGUF · Abiray | 36.0 GB | 41.8 GB | fits · 73.6 GB spare | practically identical to the original | Hugging Face → |
| Q6_K GGUF · Abiray | 28.2 GB | 34.0 GB | fits · 81.4 GB spare | very close to the original | Hugging Face → |
| Q5_K_M GGUF · Abiray | 23.9 GB | 29.7 GB | fits · 85.7 GB spare | close; small differences in fine detail | Hugging Face → |
| Q4_K_M GGUF · Abiray | 19.9 GB | 25.7 GB | fits · 89.7 GB spare | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · Abiray | 15.6 GB | 21.4 GB | fits · 94.0 GB spare | noticeable loss of detail | Hugging Face → |
Sizes from the Hugging Face file listing, read 2026-09-25. “Needed” = file + 5 GB working memory for this model + 0.8 GB kept free for the system. FP8 and INT8 files are left out on a Mac: Apple GPUs cannot compute FP8, so ComfyUI either fails to load them or converts them back to 16-bit, which saves no memory. Use a 16-bit or GGUF file.
03The text encoder
Qwen3-VL 32B: 51.5 GB as 16-bit, 27.1 GB as INT8, 15.7 GB as NVFP4. ComfyUI encodes the prompt first and can push the encoder out of VRAM before sampling, so it does not have to fit together with the model. On 115.4 GB the INT8 encoder fits on its own, so prompt encoding stays fast.
04About this GPU
A Mac with 128 GB shares that memory between the CPU and the GPU. On current macOS the GPU may use about 115.4 GB of it by default (older macOS versions: about 103.1 GB); that is the figure used here. ComfyUI can go past it, but macOS then starts compressing and swapping memory and everything slows down. ComfyUI runs on Apple GPUs through PyTorch's MPS backend. 16-bit and GGUF files work; FP8 and INT8 files do not save memory on a Mac, so they are skipped. Speed is the catch: even the fastest Macs are several times slower per image than a desktop RTX card. Chips sold with 128 GB: M1 Ultra, M2 Ultra, M3 Max, M4 Max, M5 Max (memory bandwidth 300–800 GB/s — the higher, the faster). Everything about Macs and local AI →
Mac 128 GB: 128 GB unified · ~115.4 GB for the GPU · 300–800 GB/s · Apple Silicon. Everything that runs on the Mac 128 GB →
05What more VRAM would change
Nothing to gain for this model: the Mac 128 GB already runs a top-quality file entirely in VRAM. More memory would only help with bigger images, longer clips or several models at once.
06Measured and reported results
Nobody has sent measured numbers for this pair yet. If you run MiniMax H3 on a Mac 128 GB, send your time per image and peak VRAM and it will appear here, credited.
07Questions
How much VRAM does MiniMax H3 need?
Around 21.4 GB with the smallest file (Q3_K_M) and 39.8 GB with an 8-bit file (INT8), counting working memory and a small system reserve. The full 16-bit file needs about 72.1 GB.
Which MiniMax H3 file should I download for the Mac 128 GB?
16-bit (66.3 GB) from Comfy-Org/MiniMax-H3.
Is FP8 faster than GGUF on the Mac 128 GB?
No. This GPU has no FP8 compute, so ComfyUI converts FP8 weights back before the maths. FP8 only saves memory here; Q8_0 GGUF is the closer-to-original 8-bit pick.
How much do I need to download for MiniMax H3 on the Mac 128 GB?
About 123.6 GB for the model file, text encoder and VAE listed on this page, and the same again free on disk. With a 115.4 GB card, 192 GB of system RAM or more is recommended.