750w or 850w for crossfire 7950

750 watts should be fine as long as it is a quality power supply. Corsair, Seasonic, PC Power and Cooling, XFX, Silverstone, Enermax or Antec.

For a system using two Radeon HD 7950 graphics cards in 2-way CrossFireX mode AMD specifies a minimum of an 700 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 46 Amps or greater and have at least four 6-pin PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT a crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important.

Even a Seasonic M12II-650 Bronze (SS-650AM), with its +12 Volt continuous current rating of 53 Amps and with its four (6+2)-pin PCI Express supplementary power connectors, is more than sufficient to power your intended system configuration.

Yep. I've been recommending this one recently— XFX XXX Edition 80+ Silver: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I´d get a CORSAIR Professional Series HX750 http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Eh. I don't think it's worth $30 more.

Actually I think the XFX is a better power supply. It gets a 9.7 from Jonnyguru.

Right. Corsair's coasting on the name a bit there.

Corsair needs to lose some sales to keep them honest.

Seasonic and XFX (also really seasonic) are excellent choices.

Seasonic, NZXT, OCZ, Silverstone, Thortech, XFX.

I am sure you meant to say US$20.

I think it worth as it is Modular, while the XFX is Semi-Modular.

Actually the HX 750,850 and 1050 are made by CWT.

http://www.realhardtechx.com/index_archivos/Page447.htm

And seriously, a driver update program? That costs money? lol I hope you work for them.

Semi-modular here means that the cables that will be used in absolutely every build (the mobo, CPU and two PCIe power cables) are not modular, and everything else is. It's no different from a fully modular PSU when used in a build. My price difference refers to the cost after rebates.