30-40MHz is about accurate at same vcore... extra voltage previously (with IHS) caused instability / no gains. Without IHS and with extra vcore that now doesn't cause instability, 100Mhz+ (very loosely summarised - anecdotal as bill would put it
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Mainly Clawhammers, Venice and SanDiego from my exp... not done any newcastles or semprons... results easily demonstratable with an FX tho usually...