What PSU I need for 2 6850's or in xfire or one 7850?
how much of a power supply i need tu run a couple of 6850's or one 7850. And what is a reliable brand?
Short list of good PSU mfrs: Antec, Seasonic, and Corsair. Please see my signature for a more complete list of recommended PSUs and a PSU guide.
AMD recommends a 650W PSU with at least (2) 75W 6-pin PCIe power connectors to run (2) HD6850 in crossfire. Actual power consumption is likely to be around 380W-395W at full load. http://www.guru3d.com/article/radeon-hd-6850-6870-crossfirex-review/4
AMD recommends 500W (or greater) power supply with one 75W 6-pin PCI Express power connector for a single HD7850. Actual power consumption is likely to be around 250-260W at full load: http://www.guru3d.com/article/amd-radeon-hd-7850-and-7870-review/7
AMD's recommendations will put your PSU in the efficiency sweet spot (40-70% load on the PSU) when operating a full load.
rglaredo said:how much of a power supply i need tu run a couple of 6850's or one 7850. And what is a reliable brand?
Use a PSU calculator to get the wattage size...
For a system using two Radeon HD 6850 graphics cards in 2-way CrossFireX mode AMD specifies a minimum of an 600 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 36 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.
For a system using a single Radeon HD 7850 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 26 Amps or greater and have at least one 6-pin PCI Express supplementary power connector.
Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important factor.
Reputable brands are Antec, Corsair, Enermax, Seasonic, XFX.