It's very difficult to say that an n watt PSU will handle y fine, it really does depend on the spec of the PSU, amps on the 12v rail, number of rails or even if the unit is single rail etc.
Things have changed a great deal over the years and an old "750w" PSU was far
far below what we'd expect today.
It's true to say that a good, branded 500w PSU would be happily up to the job for the most part, but one of the cheap "500w" units? *shudder* It's a mine field, though far far better than it was. I've replaced friends "1000w" super-budget PSU's with 650w decent units and seen their systems transformed - so, more stable, better clocks achievable etc.
I have however observed first hand the "power inflation" that seems to take place. Even many of these "PSU Calulator" apps get things woefully wrong. I've had PC's where I've been "advised" that I need
at least a modern, branded 850w PSU to "be on the safe side" yet I directly measure the power draw at the wall for the ENTIRE SYSTEM with monitor & speakers as well as never going over 500w peak during benching.
This is a worrying trend as the novice system builder, based on this advice, might choose the budget "1000w" PSU over the more expensive branded and respected 650w unit and have no end of troubles as a result. I've seen it happen.
So yes, the OP could have happily powered his rig with a good 500w PSU, no doubt, however he's actually already got a fairly decent mid-range 750w PSU that should equally be perfectly up to the job - if not quite as effeciently as said 500w. If the OP had some budget PoS PSU, then the advice given here would be quite different!
Scoob.
