Qwen3.8-27B-ROCmFPX-GGUF

Engine requirement: these GGUFs use ROCmFPX tensor types added to the fork in August 2026. A fork build newer than 2026-08-06 is required; older builds fail to load with tensor 'output.weight' has invalid ggml type 102. Stock llama.cpp cannot load these files at all -- for stock llama.cpp use the sibling MagicQuant repo.

Measured quality (2026-08-16, wikitext-2 PPL, ctx 512, 100 chunks, BF16 baseline 6.7443): MQ-Q6 measures 6.7412 — a tie with the stock Q6_K (6.7470). MQ-Q4 measures 6.9240 (+2.7% vs baseline), a real quality loss against its MagicQuant source (Q4_K_M: 6.7522). If quality at Q4 size matters more than fork-native types, use the sibling repo's Q4_K_M; MQ-Q4 remains the right pick only where the fork's FP4 execution path is the point.

⚠️ These files do NOT load on standard llama.cpp

They use AMD-native *_ROCMFPX tensor types from the experimental ciru-ai/ROCmFPX llama.cpp fork (build from source). For files that work with stock llama.cpp / LM Studio / Ollama, use the sibling repo: lmcoleman/Qwen3.8-27B-MagicQuant-GGUF.

Derivative of Qwen3.8-27B, quantized using MagicQuant hybrid evolutionary per-tensor search and quantized to AMD-native ROCmFPX formats (fork-only) tuned for Strix Halo (gfx1151).

Base Model

This is a derivative of Qwen3.8-27B. All credit for the base model architecture and weights goes to the original authors. The base model's license applies to this derivative.

Quantization Method

Quantized using MagicQuant hybrid evolutionary per-tensor quantization, based on the methodology by magiccodingman:

• Tensors are classified into sensitivity groups (Embeddings, Head, Query, Key, Output, FFN Up/Down, MoE Experts, Router)
• An evolutionary search finds the optimal quantization type per group, balancing size vs. perplexity
• Q4/Q5/Q6 tier targets are searched, and each one ships only if it earns its place (see below)
• Small-row tensors and sensitivity-critical layers (embeddings, output head, router) are kept at F32/F16/BF16
• This is NOT a uniform quantization -- each tensor group gets its own optimal type

A tier name here is a size band, not a promise that every tensor uses that exact type. A "Q5" is whatever mix of schemes landed in the Q5 size band with the lowest measured perplexity loss -- which is the point of the search.

Tiers this build does not produce

• Q5 -- rendering MagicQuant's Q5 config into ROCmFPX types predicts 20.68 GiB against a 50.89 GiB BF16 baseline (ratio 0.4063), which is the Q6 band, not Q5.

These were not built at all. This is a property of how the schemes round into the ROCmFPX type ladder for this particular model, not a temporary gap, so a file for them will not appear in a later build either.

ROCmFPX (AMD-native, fork-only)

These GGUFs use AMD-native quantization schemes from the experimental ciru-ai/ROCmFPX llama.cpp fork, tuned for and benchmarked on AMD Strix Halo (Radeon 8060S iGPU, gfx1151, unified memory):

• ROCmFP3/4/6/8 tensor types with straight and "agent" presets (agent presets keep tool-calling / JSON-structured output reliable at low bit-widths)
• Files load only on the fork -- it is an experimental upstream research build, so build from the pinned commit that produced these files (the default branch may have moved on since):

git clone https://github.com/ciru-ai/ROCmFPX.git ROCmFPX
cd ROCmFPX
git checkout 68f23f34c12d7e61177a034b0d8d3fea2129565e
# then build per the fork's own README

GGUF Files

File	Size	Quant	Perplexity vs BF16
Qwen3.8-27B-ROCMFPX-MQ-Q4.gguf	15.7 GB	MagicQuant Q4 layout in ROCmFPX types (hybrid, fork-only)	6.7611 (+0.25%)
Qwen3.8-27B-ROCMFPX-MQ-Q6.gguf	22.2 GB	MagicQuant Q6 layout in ROCmFPX types (hybrid, fork-only)	6.7579 (+0.20%)
mmproj-Qwen3.8-27B-f16.gguf	0.9 GB	F16 (unquantized)	not measured

Perplexity measured on wikitext-2 (100 chunks, ctx 512) against the BF16 baseline of 6.7443. Lower is better; the percentage is the increase over BF16. These are the same measurements the tier selection is based on, so a tier that shipped is one that earned its size.

Recommended: Q4 (14.64 GiB). It is the smallest tier that is statistically tied with the best measured quality here. Q6 is 41% larger for 0.048 percentage points of perplexity, which is below what this measurement can resolve -- so the extra bytes buy nothing you can detect.

Usage

Requires a from-source build of the ROCmFPX fork (stock llama.cpp, LM Studio, and Ollama cannot load these files):

# Interactive chat (--jinja uses the model's embedded chat template)
llama-cli -m Qwen3.8-27B-ROCMFPX-MQ-Q4.gguf -c 8192 --jinja -cnv

# Server mode
llama-server -m Qwen3.8-27B-ROCMFPX-MQ-Q4.gguf -c 8192 --port 8080 -ngl 99 -fa on --jinja

Vision (image input)

llama-server -m Qwen3.8-27B-ROCMFPX-MQ-Q4.gguf --mmproj mmproj-Qwen3.8-27B-f16.gguf -c 8192 --port 8080 -ngl 99 -fa on

Serving: MTP Speculative Decoding

This model includes MTP ("nextn") draft tensors, enabling self-speculative decoding -- measured ~1.6-1.9x faster generation with a ~95% first-token accept rate (no separate draft model needed; it drafts from itself):

llama-server -m Qwen3.8-27B-ROCMFPX-MQ-Q4.gguf -c 8192 --port 8080 --host 127.0.0.1 -ngl 99 -md Qwen3.8-27B-ROCMFPX-MQ-Q4.gguf --spec-type draft-mtp -ctk q8_0 -ctv q8_0 -fa on

Memory cost: MTP needs its own draft context alongside the main context, so serving with it uses roughly 2x the model's memory compared to serving without -md/--spec-type draft-mtp.

Caveats

• The base model's license (apache-2.0) applies to all derivative files
• Fork-only files: stock llama.cpp, LM Studio, and Ollama cannot load these -- build ciru-ai/ROCmFPX from source
• Quantization reduces precision -- verify outputs for your specific use case
• The hybrid quantization assigns different precision to different tensor groups, which means quality characteristics may differ from uniform quantizations

Limitations

• Quantized models may exhibit subtle differences from the full-precision fine-tune
• This model inherits any limitations and biases present in the base model

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