Nah, I've done tons of research, the calculator says that my set up will need ~830, but thats really pushing it... The main drain is a pair of 295s, but I'm only getting the second in the future, and when I do hook it up I will cut back on extras like USB devices, pci TV tuner etc. But people say that those calculators overestimate a bit and so if the whole set up is overestimated at 830 and with a couple of things removed is buzzing 800, it should be fine right???