Originally Posted by shnur
First of all, thanks a lot for this guide, it's VERY helpful and I think it saves a lot of threads
Does this includes 80+ ratings in mind?
As I'm looking at something within my rig range with an additional 6870; 650W would be perfect but kind of on the limit since I also have a watercooling system and fold most of the time (not 24/7 though).
Taking a Gold rated PSU (SeaSonic X Series X650 Gold) would give me additional freedom since it's able to go past the specs; or am I not understand this correctly?
EDIT: Or a Seasonic M12II 620W Bronze would do the job; it's a 50$ difference between the 650W Gold?
Power supplies are rated for output power to the components (DC). Good power supplies that are recommended can do their rated power in spec for hours at a time, maybe a little more (but overloading them is not good). One power supply rated for 650W may require 800W from the wall to output 650W to your computer. Another may only take 720W from the wall to output 650W to your computer.
Efficiency is therefore irrelevant when looking at what you need in terms of the labeled wattage.
Seasonic M12II 620W should be fine, but if you're looking for a modular unit around that price range, generally you may as well get something else as the M12II's price tends to be a little high for what it is.
Actually the same can usually be said for the Corsair HX650, but 100 CAD is an okay price and probably close to what the M12II was?
A unit comparable to the Seasonic X Series is the XFX Pro XXX Edition 750W, for 123 CAD before rebate: