Power Supply needed for OCed Xfire system

[Uniqueuponhim]

With the system I'm currently building I intend to do some overclocking of the CPU and RAM as well as eventually get a second video card for crossfire. As it stands I'll be getting a Phenom II X4 955, 2x2GB of G.Skill DDR3 1600 RAM, and an HD4870 video card. Eventually I'll be getting a second video card to pair with the one I have.

So I'm wondering what kind of power supply would be required to run all of this. I've been looking at the Corsair 550W and 650W PSUs (both have a single 12V rail - 41A and 52A respectively), the OCZ ModXStream 600W and 700W PSUs (both of which have two 25A 12V rails) and the Antec Earthwatts 650W PSU (Which has 3 12V Rails at 22A, 22A and 25A).

I'm leaning towards the earthwatts one right now, as it is significantly less expensive than the corsair and I'm afraid the 25A rails on the OCZ ones might not be quite enough to power both a video card and the OCed CPU at peak (since I'd have to put the CPU on a rail with one of the video cards).

So, is 650W going to be enough for what I want? A friend of mine who had a similar setup told me that her Corsair 650W wasn't able to handle everything and ended up dying. I'm not sure if it was a bad PSU or if it really wasn't enough.

Also, is the Antec Earthwatts a good name? Will the 3 rails work well for what I need? Or would I be better off spending the extra $20 on the Corsair with the single rail?

 

[tecmo34]

None of the above... To Crossfire a 4870, you need 4 PCI-e power conncectors. The PSU you have listed only have to. I recommend jumping up to this one...

CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply - Retail

 

[Uniqueuponhim]

Hmm, I'm glad I asked then. Are there any less expensive PSUs out there that would work as well? (I'm in Canada, and the Corsair 750W is $150 on newegg.ca :S )

 

[GhislainG]

Hmm, I'm glad I asked then. Are there any less expensive PSUs out there that would work as well? (I'm in Canada, and the Corsair 750W is $150 on newegg.ca :S )

You can order it from DirectCanada: http://www.directcanada.com/products/?sku=11180AC8887&vpn=CMPSU-750TX&manufacture=CORSAIR. It's less expensive and, unless you're in BC, you don't pay PST.

 

[Uniqueuponhim]

Ah, thanks. I'll do that then. Unfortunately I do have to still pay the full 13% HST since I'm in Nova Scotia, but $110 is a much better price than $150. (though still a bit more than I'd like to pay)

 

[tecmo34]

You can use NCIX's price matching for it... http://ncix.com/products/index.php?sku=26415&vpn=CMPSU-750TX&manufacture=Corsair , if that helps cut down on the 13% HST cost. All you have to do is link to DirectCanada's part page and it's price...

 

[GhislainG]

Whatever site you use, check the total cost delivered to your door. I tried NCIX before, but shipping was sometimes making them as or even more expensive.