FWIW Haswell - on which this was benchmarked - does not downclock on AVX2; it just boosts vcore and thermal throttles if the cooling solution can't keep the die

FWIW Haswell - on which this was benchmarked - does not downclock on AVX2; it just boosts vcore and thermal throttles if the cooling solution can't keep the die below ~100C (which of course, the crappy TIM plus bundled desktop heatsink have essentially zero chance of doing with many extended workloads). To preclude thermal throttling the auto-downclock-on-AVX2 was added later, I think for Skylake.