The Seasonic S12 Energy + 650 watt has incorporates a "dual magnetic amplifier" circuit to achieve a maximum ripple on the +12V line of only 3%. This works out to only a 0.36mV ripple, which, compared to max ATX spec of 120mV is very palatable. For you non math gurus out there, the Seasonic unit produce a max ripple on the +12V line one third less than the max allowed by the ATX spec. Very impressive!