It's generally a good idea to let your power supply decide when it needs a burst of air to keeps its internals nice and chilly, but if you'd rather take matters into your own hands, Cooler Master's Silent Pro Hybrid Series is a new line of fully modular power supplies that come bundled with a fan controller. With it you can turn off your PSU's fan and control up to three system fans. Sounds like a disaster waiting to happen, except Cooler Master put a safe guard in place.
When operating in fanless mode, the PSU's fan switches off and stays that way unless loads jump past 200W. At that point the fan kicks on so your power supply doesn't commit suicide, and will cool the unit according to load level. The included fan controller sports a pair of dials, one for the PSU's fan and the other for your three system fans.
The Silent Pro Hybrid Series is available in 850W ($200), 1050W ($250), and 1300W ($300) models, each one 80 Plus Gold Certified. They're also 100 percent modular, a feature Cooler Master says will come in handy when/if you decide to upgrade to a higher wattage unit within the same series. Should you find yourself in that position, you can simply detach the cables from the PSU and swap the unit out without removing the cables from your computer case.
Included cable connectors:
Motherboard 24-pin: x1
CPU 4+4 pin: x2
Molex 4-pin: x5
Fan Cable 3-pin: x3
PCI Express 6+2: x8 (1300W); x6 (1050W, 850W)
Cooler Master designed the new PSUs with a single +12V rail with 105A on the 1300W, 82A on the 1050W, and 70A on the 850W. All three models are available now.