6950 xfire on fsp raider 650w?

[megahurtz]

Hi people,
I have just picked up a 2nd 6950 cheap off ebay and am a bit worried about my psu its a fsp raider 650w unit with 668watt total power delivery.Now i know its fine for one 6950 but i am going to put in a 2nd and have checked on the extreme power supply website with my set up it say's toal req's is 550 with my system specs.So in theory i should be ok but i dont know about real world situations.So any input would be greatly appreciated.

full specs=
i5 3470 @ 3.4 turbo to 3.6
8gb ddr 1600 ram
2x 320gb hdd
2x6950's xfire
dvd burner
2x120mm bitfenix led fans
2x120mm non led fan's
pci wifi card
stock cooling.
thanks heazps ghy's (and or girl's)


ps, i dont know if this relevant but i also have a samsung s27a950d 3d moniotr that i run @ 120hz

 

[bemused_fred]

650 watts should be enough for your fairly power conservative CPU and the two cards in crossfire.... just.

http://www.tomshardware.co.uk/fx-overclock-crossfire-ssd,review-32342-12.html

However, the real problem is that each 6950 needs 2 PCIe power pins and a 650w PSU is unlikely to have 4 PCIe pins. You could always use some Molex-to-PCIe pins if you're short, but bear in mind that you need 2 molex for each PCIe pin. So if your current power supply has only 2 PCIe power pins, you'll need to utilize 4 molex cables to be able to power the second card. And considering the number of fans and peripherals you have, I don't think thatllbe possible. Frankly, just due to the shortage of wires, you'll want a 750W unit that has 4 PCIe power cables.

I suggest:
http://www.corsair.com/power-supply-units/tx-series-power-supply-units/enthusiast-series-tx750-v2-80-plus-bronze-certified-750-watt-high-performance-power-supply.html

 

[megahurtz]

Ok well i have all my fans running off my mobo fan headers and also i have 8 molex plugs that are not being used and also i have molex to vga adapters that use one molex with a yellow wire that loops through one of the back of the 6 pin vga connectors into the back of the one bellow it i know that you never used to be able to get adapters that use one and i have only ever seen this once.http://compare.ebay.com.au/like/321045695265?ltyp=AllFixedPriceItemTypes
but even if i have to use it and then a standard twin molex adapter its no probi was just worried that if oc the cards in xfire it might shut down on me.

 

[bemused_fred]

That still might happen. Even with a fairly efficient CPU, you're gonna be running damn close to the maximum limit of the PSU.

 

[megahurtz]

That still might happen. Even with a fairly efficient CPU, you're gonna be running damn close to the maximum limit of the PSU.

Oh well i get in the morning ill put it in overclock the heck out of both of em run a few benches and report back ill tell ya what colour the sparks were.

 

[UDin]

Bro...FSP raider 650w only have 3molex while u need 4molex...how you power your second GPU????