PostmanPot
Honorary Master
I'm running an AMD 965BE OC'd with a GTX460, 3x12cm fans and 3x1Tb Seagate HDD's on a Corsair HX650W with zero issues and no sound from the PSU (I'm a silence freak). I do not see why the OP needs a bigger PSU for his setup
Nor do you. But the reason your PC is [relatively] silent is largely to do with your over-spec'ed PSU.
http://www.corsair.com/power-supplies/modular-psus/professional-series-1/hx650w.html
Note the 'Tech Specs', the fan only starts getting loader at about 325watts usage - which is ± what the average mid - high end, single gfx card PC would use at full load.
Therefore, as per my post, budget = Corsair CX500, or if you have more to spend and value quiet computing get a higher wattage PSU.