KV Cache quantization benchmark: 170k context on RTX 5090

Opening-Broccoli9190 · reddit · 2026-08-15

Benchmarking Qwen 3.8 27B on an RTX 5090, comparing the impact of different KV Cache quantization strategies (Q80, Q51, Q40) on maximum stable context length. Results show that lower precision KV Cache (Q40) significantly extends the context window to 169,984 tokens, though users should watch for potential performance regression. Detailed build flags and llama.cpp configuration are provided.

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