Cooler Master gx550 w

I'm pretty sure that the Cooler Master GX-550W is for more than capable of running an HD 5850. As for CrossFire - no, it wouldn't be possible to run two HD 5850s, simply because one HD 5850 needs two 6-pin PCI-e connectors, and two would need four. The PSU you suggested only has two, i.e. enough for one HD 5850.

Although, it might be possible to CrossFire two HD 5770s or 5750s, as they only use one six-pin connector, and I have heard people running two HD 5770s on high-quality 500-550W PSUs.
 
The Coolermaster GX-550 is not a stellar performer but it is adequate. The power supply is not sufficient for a system two ATI radeon HD 5850 cards in Crossfire mode.

Here are the official power requirements for the ATI Radeon HD 5850 and HD 5870 video cards.


ATI Radeon™ HD5850 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

500 Watt or greater power supply with two 75 watt, 6-pin, PCI Express® power connectors.

600 Watt or greater power supply with four 75 watt, 6-pin, PCI Express® power connectors for ATI CrossFireX™ technology in dual mode.


ATI Radeon™ HD5870 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard.

500 Watt or greater power supply with two, 75 watt, 6-pin, PCI Express® power connectors.

600 Watt or greater power supply with four, 75 watt, 6-pin, PCI Express® connectors for ATI CrossFireX™ technology in dual mode.

The power supply recommendations are for an entire pc system.

Corsair and Seasonic are two brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty. Lately we've been seeing a few other brands offering some high quality units. One example would be the Antec Earthwatts and Antec TruePower New models which are a major improvement over Antec’s older psu’s like the Basiq models.
 
This PSU from CM has been made by Seventeam and it is enough to power the 5850.
Anyway I would recommend you, as an alternative, the CORSAIR VX550. This PSU has a solid reputation. That is not a surprise if we consider that it has been made by Seasonic which is one of the best psu manufacturers.
If you are seriously thinking about doing 5850cf, I would recommend you to buy a CORSAIR HX650 at least, although the HX750 model is a better choice. Both PSUs have been made by CWT (another fantastic psu manufacturer).
 


actually u can use a molex to pcie converter
 



The damn thing will be inside your case all the time! Who cares wtf it looks like, as long as it works fine! [:lectrocrew:1]

It could be green with red checkers on it for all i care, i would never pay more for a ''better looking'' psu, that's dumb! [:lectrocrew:7]
 
fine ill look into the matter... Another question is there but i didn't wanna post it in a new topic... Is the msi g31m2 v1 motherboard a pcie x16 1.0a or 1.1 board.. Cause msi website lists it as 1.0a while intel says that g31 boards are 1.1.. Also will the 5850 work on there boards..