PC Power & Cooling, a brand from OCZ, has a new 750W PSU in its Silencer Mk III product line. Like the name suggests, it's a silent power supply, completely silent actually up to 350 watts. Hardware.Info tested this semi-passive PSU.
The PC Power & Cooling Silencer Mk III 750W works according to the single-rail principle. It can supply up to 62 A at 12 V, almost its entire capacity (744 watts), at this voltage. It's a (semi-)modular PSU, and you have to screw the cables into place. The cables for the motherboard and the CPU, are permanently attached to the PSU. The PSU has two sets of 4/8-pin CPU connectors, so you'll likely end up an unused cable anyway. All of the modular cables are sleeved, and the casing of the PSU is white.
The Silencer Mk III 750W has an 80 Plus Gold certification, which means its should be around 90 percent efficient. It comes with four molex, 12 Serial ATA and four PEG connectors. The PSU has a 14cm fan, and switch on the back let's you switch between normal mode (the fan is always on and temperature controlled) and semi-passive mode.