Run Qwen 3.8 Flash Next (Qwen 4) 180B on CPU Only, No GPU Needed

#29
by laxmimerit - opened

We ran the 180B Qwen3.8-Flash-Next on one desktop with no GPU at all, then added a single RTX 5090, and measured speed and answer quality against Qwen 3.8 27B.

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We found that its 1-bit build is 40 percent lookup table, and we finished at 52 tokens a second on a machine that costs less than one of those cards.

Key takeaways:

  • Every 4-bit build of this model is 93.7 GB or larger, so a 96 GB desktop has to run the 1-bit or 2-bit build.
  • The 1-bit file is 72.5 GB because its 26.82 GiB n-gram table is stored at 4-bit. That table does pure lookup, so it belongs in system RAM and nowhere else.
  • Only about 3.6 GiB is dense weight touched by every token, which is why a 32 GB card can carry the part that matters.
  • On the CPU alone we get about 11 tokens a second, and prompt reading keeps improving all the way to 24 threads while generation flattens after 8.
  • With -ot per_layer_token_embd=CPU and -ncmoe tuned one step short of the cliff, we get 52.0 tokens a second. One step further is 3.7, with no error message.
  • A 1-bit 180B model scored 4.01 perplexity against 5.68 for a 4-bit 27B, and answered every finished problem correctly, while the 1-bit 27B invented three scientists and a JSON field.

๐Ÿ”— Full Teardown is available here: https://kgptalkie.com/tutorials/llm-benchmarking/qwen-3-8-flash-next-on-cpu-only

Happy Qwenning!

I have 32 gb ram + 16 gb vram 5070ti gpu...
Then can I run this model....

Can you compare Qwen 3.8 Flash (IQ 4 quants) to 27b at Q8 K XL in terms of intelligence?

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