Absolutely it has to do with higher amperage and lower ripple
MY 560W silverstone saw the end of its life in an overclocking rig when I went to a 900W fortron modular (rippple fixed with a recapping) OCs just exploded.
When I got a nice deal on a 950W corsair single rail PSU and tried it out... well that fortron went bye bye.. My OCs improved yet again!
Now for comparisons sake... the 560 -900 W jump was on AMD and the 900-950W jump was on i7. But considering the 560W could not handle a 920 AMD quad and a couple of 4850s OCed to snot on air.. Pretty sure it would have caused an EMP bang the first time I OCed the i7 rig