Can I Run Nex-N2.5 on Apple M3 Ultra?
作者： Jakub Rusinowski · 最后更新： 2026年9月8日
Yes, comfortably — Nex-N2.5 Pro at Q4_K_M needs 244.7 GB at 8K context (239.7 GB weights + 5 GB KV cache/overhead), leaving ~139.3 GB of the Apple M3 Ultra's 384 GB usable memory, at ~33 tok/s (est.), with room for up to 256K context.
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Apple M3 Ultra Specs
| VRAM | 512 GB unified memory |
| Memory Bandwidth | 819 GB/s |
Nex-N2.5 Pro on the Apple M3 Ultra: VRAM by quantization
| Quant | VRAM needed | Fits 512 GB? | Max context | Whole PC |
|---|---|---|---|---|
| F16 | 799 GB | ✗ No | — | — |
| Q8_0 | 426.8 GB | ✗ No | — | — |
| Q6_K | 330.6 GB | ✓ Yes | 64K | — |
| Q5_K_M | 286.4 GB | ✓ Yes | 128K | — |
| Q4_K_M | 244.7 GB | ✓ Yes | 256K | — |
| Q3_K_M | 174.2 GB | ✓ Yes | 256K | — |
| Q2_K | 135.5 GB | ✓ Yes | 256K | — |
Assumes an 8K-token context with an f16 KV cache, on an estimated architecture — this model publishes no config we can read. A longer window needs more; a quantized KV cache needs less. “Max context” is the largest window that still fits in 512 GB of unified memory. Figures are estimates from parameter count, quantization and memory bandwidth — the analyzer lets you tune KV-cache quant and context.
Context costs VRAM too. At Q4_K_M on the Apple M3 Ultra: 8K 244.7 GB · 32K 257.4 GB · 128K 308.1 GB. Every window this model publishes still fits 512 GB.
No compatible GPU? Nex-N2.5 on 24 GB of system RAM, CPU only: runs, but it is tight.
Nex-N2.5 Sizes That Fit the Apple M3 Ultra (at 8K context)
| Nex-N2.5 Pro | Q4_K_M · 244.7 GB at 8K context · ~33 tok/s (est.) |
| Nex-N2.5 mini | Q4_K_M · 23.8 GB at 8K context · ~110 tok/s (est.) |
Nex-N2.5 needs ~245 GB but this GPU has 512 GB. Rent a 8× H100 (640 GB)-class GPU by the hour instead of buying one:
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Cloud rates verified 2026-07 — estimates, and marketplace prices vary. Buying price is GPU MSRP only, not a full PC.
FAQ
Does the Apple M3 Ultra have enough VRAM for Nex-N2.5?
Yes, comfortably — Nex-N2.5 Pro at Q4_K_M needs 244.7 GB at 8K context (239.7 GB weights + 5 GB KV cache/overhead), leaving ~139.3 GB of the Apple M3 Ultra's 384 GB usable memory, at ~33 tok/s (est.), with room for up to 256K context.
Which quantization of Nex-N2.5 should I use on the Apple M3 Ultra?
Nex-N2.5 Pro at Q4_K_M quantization needs 244.7 GB at 8K context (239.7 GB weights + 5 GB KV cache/overhead), estimated ~33 tokens/sec, up to 256K context.
Every Nex-N2.5 size on the Apple M3 Ultra
| Size | VRAM at 8K | Verdict | Speed |
|---|---|---|---|
| Nex-N2.5 Max | 967.4 GB | Does not fit | — |
| Nex-N2.5 Pro | 244.7 GB | Runs | ~33 tok/s |
| Nex-N2.5 mini | 23.8 GB | Runs | ~110 tok/s |
Popular Models on the Apple M3 Ultra
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← Can I Run It? | Nex-N2.5 Model Page | Apple M3 Ultra GPU Page | VRAM calculator | Check Your Hardware