Problem with ASUS 8800GTS

Hi,

Having a major problem booting up my PC after installing the 8800GTS. Power comes on for like 5 seconds or so then goes off. The card has been connected to the power every which way I can think of, & only booted up once, but when I shut down after installing the drivers, nothing!!
Have a 600w PS, & a ASUS M2N32-SLI Premium motherboard so no compatability probs!
PC runs fine with my old card, but hates this one.
I’m just wondering if I need to upgrade my PS to 700W which has a dedicated PCI express lead already installed.
If anyone has any ideas, please let me know.