Minimum psu for crossfire 6850's

[SuperDuperMe]

Hey all, basically, im upgrading my computer in a few weeks, but intend to crossfire my 6850 later next year, what is the minimum psu required for 2 hd 6850 on a 1090t system with minimal overclocking (if any at all).

I currently have an old corsair hx 620 watt would this be enough or would this be pushing it?

EDIT: just to clarify i mean the absolute minimal amount of money i would have to spend in GBP/UK to get crossfire up and running safetly not minimum watts.

 

[johnb35]

A good 650 watt single rail psu would work as I noticed the hx620 has 3 rails.

 

[SuperDuperMe]

Thanks John, would this allow for small overclcoking?

 

[johnb35]

With the tx650 from corsair, it leaves you some room for overclocking. According to Linkin's psu guide here...

http://www.computerforum.com/186629-power-supply-psu-tech-guide.html

You need a 650 with 42 amps on the 12 volt rail. The tx650 has 53 amps. There are other options besides the corsair though.

 

[SuperDuperMe]

What would be the cheapest route, but safe. Thats probably the major point, being safe with it, i want it to be cheap but not enough to compromise my build.

Do you have any recommendations for the cheapest unit possible without compromising on quality.

 

[johnb35]

Xfx - http://www.newegg.com/Product/Product.aspx?Item=N82E16817207014

Ocz - http://www.newegg.com/Product/Product.aspx?Item=N82E16817341051

Corsair - http://www.newegg.com/Product/Product.aspx?Item=N82E16817139020

 

[SuperDuperMe]

thanks for the help john, ill check the uk prices.

 

[Okedokey]

The original PSU is fine even with overclocking. The 6850 is by no means powerful. Absolutely no need to buy a new PSU for an additional 3A on the 12V rail. 2 X HD6850 pull a max of 300W (TDP 127W each) when overclocked. Thats 25A, leaving 25A for the rest of the system. Heaps.

If you want to spend $100, add it to your CF 6850 budget and instead get a GTX580. That too will work on this PSU and will be faster for almost all games. You then have the potential to add another in a year or two if you wish.

But either way, if you're happy with the 6850 in CF, thats cool, the current PSU will work just fine.