This research investigates how simulated 4-bit KV-cache quantization disrupts Top-k Mixture-of-Experts routing by pushing tokens across discontinuous decision boundaries. The authors introduce a causal apparatus to quantify the Route-Mediated Fraction (RMF) of performance degradation, finding that approximately 31% of the total damage in OLMoE-1B-7B stems from these route flips rather than direct numerical precision loss. The study provides empirical evidence and detection limits but proposes no new mitigation strategies for this routing instability.
- 31% of quantization damage in MoE models is caused by expert routing flips, not just precision loss.
- Top-k routing discontinuity makes models sensitive to small numerical disturbances in KV-cache.
- The paper offers a causal detection framework but no solutions to fix the route-mediated damage.
- Findings are validated across three architectures using pre-registered probes and token-level attribution.