PSUCalc

tried it 2 months ago but didn't find better or even as good as extreme outervision online calculator.in my opinion extreme vision is the best psu calculator because of its large database of components which gets updated & realistic power requirements with various options.some online psu calculator give highly exaggerated values like asus.someone here reported that asus calculator gave him a recommendation for 1200W when he was using a 650W which should be the one to be recommended & what he was using.

Heads up: It requires .Net framework 4.0 to work.
Will have to try later.