Hello all! I'm looking for some assistance in selecting a power supply (PS). I've tried some sizing tools and am getting suggestions of ~800W. Posters on this forum have indicated that these sizing calculators often overestimate the power supply requirements so I figured I'd post a thread. My build is going to be as follows: i5-3570K Asus P8Z77-V Pro 16GB Ram (haven't picked it yet) Gigabyte WF3 7970 GV-R7970C-3GD 1 HDD for now but could increase up to 6 Case is Corsair 550D I do not plan to overclock until I am no longer able to play current games at acceptable settings. The computer will be on for most of the day and I plan to donate runtime to Standford's protein folding initiative or something of that nature. I live in Canada. My selection criteria are as follows: - Energy efficient, Gold or higher - < $150 and preferably closer to $120 or even lower - "Clean". I don't fully understand this beyond knowing that it's important. - Reliable above all else - Quiet If it becomes difficult to get everything, I welcome a wattage recommendation alone. I would also appreciate your thoughts on whether I should buy a PS for my current needs and get a new one if I choose to overclock or if I should buy one for potential future needs. Thanks for any input!