I have an overvolted Phenom II X6, overvolted GTX470, 3 hard drives, a SSD, 4 sticks of DDR3 RAM, also overvolted, and one DVD burner. This all adds up to around 550W of power, according to the PSU calculator:
http://extreme.outervision.com/psucalculatorlite.jsp
Now I want to run Folding@Home CPU+GPU. The problem is before on my Athlon XP I could run it 24/7 with no noticeable increase in noise, because the fan didn't have thermal control, and besides it didn't get that hot to begin with. But now, folding on an overclocked+overvolted CPU+GPU, I can quite confidently say that my Seasonic S12II-520W PSU is working full time, and when it does, it gets incredibly noisy, although it still can't beat my Octane (I already have aftermarket coolers on the CPU+GPU, much quieter). So I'm in the market for a PSU that'll handle my configuration while making as little noise as possible.
Enter the Seasonic X760. Tons of rave reviews. Problem is the cost. 190EURs for a 760W power supply is a hard pill to swallow especially when I can get a Corsair TX750 for half the price, throw in a Bluray burner, and still end up spending less than the X760. I heard that the X760 is very quiet. How much quieter though, does the fan start up at 550W? I don't really know. According to Corsair's site, the TX750 emits 35 decibels at 600W. I guess that's... good?