What PSU for 7950 Crossfire system?

[Haider]

Hi,

How do you calculate what PSU wattage you need? Model recommendations most welcome.

The system: -
ASRock B75M Pro3-M
Corsair CML8GX3M2A1600C9 LP Vengeance 8GB (2 x 4GB) 1600MHz CL9
Intel Core I5-3470 Processor (3.20GHZ, 6MB Cache, Socket 1155)
AMD 7950 GPU x2 Xfire


Thanks
Haider

 

[lehtv]

First off, you can't crossfire the 7950 on a B75 chipset motherboard. You need a Z77 motherboard with x8/x8 PCIe capability, e.g. Asrock Z77 Extreme3 (cheapest).

The simplest way to go about calculating the needed PSU wattage for an average system is stick to reputable brands and manufacturers, and pick any PSU with the necessary PCIe connectors. 7950 crossfire can require anything from four 6-pin to four 8-pin connectors, it depends on the model. Any decent 700W+ unit will have the necessary connectors, and some 650W units also have four PCIe connectors.

In practice an i5 + 7950 crossfire rig will consume about 300-350 watts during gaming, assuming they aren't overclocked, so you could get away with a high quality 500W unit if it had the necessary connectors.