Graphics Card Troubles

Hey all ! I bought a new PSU and Graphics Card. I bought a thermaltake toughpower 850w psu and an XFX 8800GT xxx edition 512meg 670Mhz SLi.
Well I set it all up plugged all power cables in a needed to, but as soon as I press the ON button on the computer it will have like a little spurt of power from about 1 second then turn off and won't work again. So I tried everything but nothing worked, I then took the graphics card out and put my old Graphics card in and it works fine.

My specs are

Asus m2n32-sli deluxe mobo (wifi version)
AMD Athlon64 x2 6000+ cpu
2 gb Corsair DDR2 ram
albatron 6800gt (old card)
flexiglow 500w psu (old psu)

xfx 880gt xxx edition 512mb (new card)
thermaltake toughpower 850w (new psu)

So any queries on why it would do that.

Thank You

 

try a different power cable for the video card, maybe that rail is faulty or something. Maybe try a different PCI-E slot as well since it's an SLi mobo

 

Thx for the reply I tried everything i could, even tried it an my older pc but still no luck. I took it back and the store tested it and it was faulty. They just replaced it for me now i have no troubles.. THxx