GLM-5.3-Flash Phobos GGUF

GLM-5.3-Flash on one NVIDIA GPU plus system RAM, for Phobos.

License: MIT Base model GitHub

GGUF quantizations of zai-org/GLM-5.3-Flash, made for Phobos (a fork of Strata): its engine runs the model on a single NVIDIA card and a large amount of system RAM, and serves a web chat and OpenAI / Anthropic compatible endpoints for coding agents such as Claude Code.

Files

quant file size for status
IQ4 GLM-5.3-Flash-Phobos-IQ4.gguf 179.1 GB (166.8 GiB) 24 GB+ GPU, 192 GB+ RAM available, tested
Q3 16-24 GB GPU, 64 GB RAM + NVMe coming, being measured
Q2 (experimental) 16-24 GB GPU, 64 GB RAM + NVMe coming, being measured

Shared by every quant:

file size what
expert-profile-agent.strp 100 KB optional: which experts to put on the GPU first, measured on coding-agent traffic
tokenizer/ 7.5 MB vocab, merges and chat template, extracted from the GGUF
needles/ 2.2 MB 6 long-context test prompts (95 K and 113 K tokens), for test reports
LICENSE Z.ai's MIT license for the weights
SHA256SUMS sha256 of every file

No numbers are promised for the Q3 and Q2 until they are measured.

Headline numbers (IQ4)

One Tesla V100 32 GB (PCIe 3), 2 x Xeon Gold 6252, 376 GB RAM, AVX-512 VNNI path, quiet machine:

measured
reading a long prompt (95 K and 113 K tokens) 616-626 tokens/s (113 K tokens in 181 s)
writing at 95-113 K tokens of context 29-33 tokens/s
writing, short context 26 tokens/s
first token of a follow-up turn (200 new tokens) 1.1 s
needle-in-a-haystack at 95 K and 113 K tokens 6 / 6 found

The long-context writing figures come from the needle answers, which are short and predictable: speculative decoding accepts most drafts there. Expect less on free-form writing. More below.

How it runs

flowchart LR
    subgraph GPU["GPU: VRAM"]
        T["attention trunk<br/>MLA + sparse indexer, linear attention, MTP head"]
        H["hot experts<br/>the most used, about 11 %"]
    end
    subgraph HOST["CPU: system RAM"]
        C["all other experts<br/>IQ4, int8 kernels (AVX-512 VNNI or AVX2)"]
    end
    T -- "token activations" --> C
    C -- "expert outputs" --> T
    T --> H
    H -. "adaptive tier: swaps experts as traffic changes" .- C
  • The attention trunk and the most used experts (1353, 17.2 GB on our V100) live on the GPU.
  • The other experts stay in RAM; the CPU computes them with int8 kernels.
  • The model's own MTP head drafts tokens for speculative decoding (--spec 1).

What is in the IQ4 GGUF

tensors type
routed experts, gate and up IQ4_XS (4.25 bits per weight)
routed experts, down IQ4_NL (4.5 bits per weight)
the rest of the trunk (attention, dense and shared feed-forward) Q8_0
332 small trunk tensors: MLA projections, hyper-connection mixers, the sparse-attention indexer, linear-attention gates BF16
norms F32
  • Expert payload 168.8 GB of the 179.1 GB.
  • The MTP layer (the model's own draft head) is kept.
  • Made with llama.cpp's llama-quantize from unsloth's BF16 GGUF, with unsloth's importance matrix.
  • Every expert quantization type was checked against llama.cpp's reference kernels on the CPU (AVX-512 VNNI) and on the GPU.
  • Architecture glm5-next (llama.cpp mainline). The file uses only mainline tensor types. We have not tested it in llama.cpp itself.
  • Text only. GLM-5.3-Flash is natively multimodal. This GGUF and the engine handle text; images are not supported.

What differs from other GGUFs of this model

unsloth's closest file, UD-IQ4_XS, is 156.8 GB in 5 shards:

  • gate/up experts mostly IQ3_S;
  • down experts IQ4_XS, with Q4_K / Q6_K in a few layers;
  • the small trunk tensors in Q8_0; the output in Q6_K.

Phobos's engine needs IQ4_XS gate/up and IQ4_NL down in every layer, so it cannot run unsloth's files. This one has:

  • All experts at 4 bits, the trunk at 8. The types match the engine's expert kernels:
    • the CPU repacks the IQ4 experts at load for its AVX-512 VNNI path;
    • the GPU reads them as they are;
    • the trunk always sits on the GPU, so it gets Q8_0.
  • An expert profile measured on agent work. The 100 KB profile ranks the experts by how often a coding agent's traffic routes to them.
    • Source: ~74 K tokens of real Claude Code sessions run through llama-imatrix. It stores counts only, none of the text.
    • With it, the GPU starts with the experts an agent uses most. Without it, the engine starts from its own ranking.
    • Either way, the adaptive tier then learns from your traffic.
    • The profile is not the quantization's importance matrix: the weights use unsloth's.

Speed in detail (IQ4)

Same machine; 1353 experts (17.2 GB) in VRAM; 2 conversations of 131072 tokens each; --spec 1.

Writing (decode), short context, quiet machine:

CPU kernel path tokens/s
AVX-512 VNNI, R8 layout (the default on this CPU) 26.0
AVX2 (AVX-512 switched off with GLM_CPU_ISA=avx2) 21.1

Time to the first token for a follow-up turn of N new tokens:

new tokens VNNI AVX2
200 1.1 s 12.3 s
800 2.3 s 14.8 s
2000 4.3 s 16.3 s

The AVX2 path uploads its prompt experts to the GPU instead of sharing the work with the CPU. On PCIe 3 it is bound by that upload.

Long conversations, 95-113 K tokens of context:

VNNI, quiet VNNI, under background load AVX2, under background load
writing 29-33 tokens/s 21-25 tokens/s 22-25 tokens/s
reading a new long prompt (cold) 616-626 tokens/s (113 K: 181 s) ~600-680 tokens/s ~440 tokens/s
  • At this length, a whole AVX2 turn takes ~1.3-1.4x as long as on VNNI.
  • Loading takes ~2 min from NVMe.
  • Desktops (projected, not measured): 2-channel DDR5 gives ~55-60 GB/s against ~280 GB/s here; expect roughly 10-15 tokens/s writing. A 24 GB card also holds fewer experts than our 32 GB one.

Requirements (IQ4)

minimum better
OS Linux x86-64 (WSL2 being verified)
RAM 192 GB 256 GB+ (room for the prefix cache)
GPU NVIDIA, compute capability 8.0+ (RTX 30 / 40 / 50, A-series), 24 GB more VRAM: more experts on the GPU
V100 (sm_70) as an experimental build
CPU AVX2 AVX-512 VNNI (Xeon Cascade Lake or newer, AMD Zen 4 / Zen 5)
Disk ~180 GB, NVMe
  • Memory bandwidth sets the speed: each generated token reads ~3 GB of experts from RAM.
  • 192 GB of RAM rules out most desktops; AM5 and LGA1700 / LGA1851 boards with 192 GB+ work.
  • Intel LGA1700 / LGA1851 have no AVX-512, so they run the AVX2 path.

Tested hardware

GPU what was tested
Tesla V100 32 GB (sm_70, experimental build), 376 GB RAM the full model: every number above, long-context needles 6/6 at 95 K and 113 K tokens (VNNI and AVX2)
RTX 3080 10 GB (sm_86), WSL2 a mini model only (the real engine, a few experts per layer): all 18 checks pass, the WSL2 pinned-memory path included
24 GB cards (RTX 3090, 4090, ...) untested: reports welcome (see below)

Run it

pip install -U huggingface_hub
hf download mussonking/GLM-5.3-Flash-Phobos-GGUF \
    --include "GLM-5.3-Flash-Phobos-IQ4.gguf" "expert-profile-agent.strp" "tokenizer/*" \
    --local-dir /models/glm

Then build Phobos and start the server: quick start. The server starts the engine for you:

glm_serve --gguf GLM-5.3-Flash-Phobos-IQ4.gguf --profile expert-profile-agent.strp \
          --ctx 131072 --sessions 2 --kv-latent auto --spec 1
  • Greedy decoding only.
  • One GPU, one request generating at a time.
  • Thinking effort: Low, High or Max (reasoning_effort). No effort means Max, the model's default.

Report a test

You can help if you have a 24 GB card (3090, 4090, ...), a desktop with 192 GB, or WSL2. Open an issue on mussonking/Phobos with:

  • curl http://127.0.0.1:8142/health: the JSON. It includes cpu_isa, the expert layout and the number of VRAM slots;
  • the engine log;
  • the needle results: tools/glm/needle_http.py needles/ --url http://127.0.0.1:8142 --key-file <file> (in the Phobos repo), with this repo's needles/.

Credits

  • Z.ai: GLM-5.3-Flash, its weights, tokenizer and chat template (MIT, Copyright (c) 2026 Z.AI Co., Ltd; see LICENSE).
  • unsloth: the BF16 GGUF conversion this file was quantized from, and the importance matrix used to quantize it (MIT).
  • llama.cpp / ggml and their authors (MIT): the IQ4_XS / IQ4_NL formats, llama-quantize (which made this GGUF), llama-imatrix (which measured the expert profile), and the glm5-next implementation the engine's forward pass was written from.
  • Strata by Niko1221 and the Strata contributors (MIT): the project Phobos forks.
  • The research behind the architecture: Multi-head Latent Attention (DeepSeek-V2, arXiv:2405.04434); DeepSeek Sparse Attention (DeepSeek-V3.2, arXiv:2512.02556); Kimi Delta Attention (Kimi Linear, arXiv:2510.26692, after Gated DeltaNet, arXiv:2412.06464); mHC (arXiv:2512.24880, after Hyper-Connections, arXiv:2409.19606).
  • Related work, no code shared: sergqwer/strata-glm (NVFP4 experts on an RTX 5090; archived), glm53-flash-offload by 0xSero (exllamav3, EXL3 3.05 bpw, RTX 3090).

Not affiliated with or endorsed by Z.ai, unsloth, the llama.cpp authors or Strata's author.

License

  • Weights: MIT, Z.ai's (zai-org/GLM-5.3-Flash; LICENSE in this repo).
  • Expert profile, needle prompts, this card: MIT, Copyright (c) 2026 mussonking.

If you use the model, cite Z.ai's report:

@misc{glm5team2026glm5vibecodingagentic,
  title={GLM-5: from Vibe Coding to Agentic Engineering},
  author={GLM-5-Team},
  year={2026},
  eprint={2602.15763},
  archivePrefix={arXiv}
}
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