A high-performance open-source engine that runs a 125B mixture-of-experts Qwen3.8-Flash-Next (NVFP4) on two 16 GB consumer GPUs by tensor-parallelizing most computation across the cards and offloading the routed experts that don’t fit in VRAM to host RAM/CPU. The design uses PCIe tensor-parallelism without peer-to-peer, a VRAM cache partitioned by expert id, and an AVX-512 NVFP4 CPU kernel to compute missing experts; it supports MTP speculative decoding (K=3), INT8 KV with an elastic KV/expert-slot budget up to 262,144 tokens, prefix caching across turns, and an OpenAI-/Anthropic-compatible server. The same binary also serves a dense Qwen3.8-27B. It is a two-GPU fork of ninfer-tp2 (renamed capy-flash) and ships with install scripts, serving profiles, and measured development logs.
Benchmarks on a Ryzen 9 9900X with 2×RTX 5070 Ti (16 GB) show strong throughput and responsiveness: prefill speeds reach ~3.8k-4.0k tok/s for long prompts; agentic replay median time-to-first-token 1.82 s and decode 100.8 tok/s (total 243 s) versus Strata NVFP4 at 2.42 s and 78.3 tok/s (314 s). Accuracy is comparable to an NVIDIA GB300 NVFP4 reference on GSM8K and MMLU-Pro. Agentic task runs solved 20/20 cases with no malformed tool calls and produced ~42.9k generated tokens per run. Requirements include Linux, CUDA 13.1, two sm_120 GPUs (RTX 50-series 16 GB), an AVX-512 CPU, ~70 GiB free RAM and ~135 GB disk (64.6 GiB page-locked host allocation for experts). Versioned release: v0.5.4.
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