Requirements
This checkpoint does not run on stock vLLM. It needs a vLLM build carrying
the RDNA2 DeepSeek-V4 patches, and --dtype float16.
Target configuration is 8 gfx1030 dies across 2 nodes (PP=2 x TP=4):
vllm serve yiminyuan/DeepSeek-V4-Flash-0731-INT4-W4A16 \
--dtype float16 \
--tensor-parallel-size 4 \
--pipeline-parallel-size 2 \
--trust-remote-code
--kv-cache-dtype may be omitted; it resolves to fp8_ds_mla, the only layout
these backends implement.
Quantization
Table | |
|---|
| Method | compressed-tensors, pack-quantized |
| Scheme | INT4 symmetric, group size 32, weight-only (W4A16) |
| Scope | routed experts only (w1/w2/w3/gate_proj/up_proj/down_proj/gate_up_proj) |
| Untouched | attention, shared experts, router gates, norms, embeddings, lm_head, MTP heads |
The source weights are already 4-bit (FP4 e2m1 with UE8M0 block scales), so this
is a transcode rather than a fresh quantization: each expert is dequantized
bit-exactly and re-encoded as symmetric INT4. Tensors stored as FP8 elsewhere in
the model are converted to fp16 bit-exactly.
Fidelity
Every one of the 35,328 transcoded expert tensors was compared against the
dequantized source:
Table with columns: SNR (dB) | SNR (dB) |
|---|
| minimum | 22.71 |
| 1st percentile | 23.15 |
| median | 25.69 |
No range violations. All 390 FP8 to fp16 conversions are bit-exact.
Verification
Run end to end on 4 gfx1030 dies (one Radeon Pro W6800X Duo pair, 128 GiB) with
CPU offload, --dtype float16, TP=4:
- Coherent greedy generation and correct answers through the chat template.
- Perplexity 2.42 (prose) and 1.72 (code) on held-out text.
- 3,011-token prompt exercising the sparse attention indexer, summarized correctly.
The 8-die, 2-node configuration above is the deployment target and has not been
run yet.
Limitations
- fp16 only; bf16 is untested here and the RDNA2 kernels this targets are fp16.
- The router, shared experts and attention stay at full precision, so the memory
saving is confined to the routed experts.
- Quality has been checked for coherence and perplexity, not with a benchmark
suite; treat published scores for the base model as an upper bound.