X1950XT start-up problems

Ok guys, recently built a new PC and am having troubles with my 1950xt. When I start up the pc it reboots after a few seconds then starts up again in a continuing cycle. I'm running a C2d e6400, 2gb DDr2-800 ram (budget) and a Gigabyte 965 mobo, I've tested the system with another graphics card (Sapphire 7000 PCI) and it seems to work fine so i'm pretty sure its not the RAM. Anyone got any ideas where to start?
Cheers

Most obvious question is your psu...what brand?How many amps on your 12 volt rails?This is likely your problem

take the card out and then re install it, and then see if it works, i have a X1950xt and it works flawlessly

Go to:

http://extreme.outervision.com (Power supply calculator)

and add one Hard Disk, one optical drive, video card and CPU, use high end motherboard,
calculate Watts and divide by 12 to get amps. Add 2-4 amps for safety.

Compare to your power supply 12v rails.
Combined should not exceed requirements.

Max power output on 12v rails: look at box, subtract 3.3v + 5v maximum output from total
wattage of PSU and divide by 12 to get maximum amps on 12v rail. Should be higher than
requirements. That's why we add 2-4 amps.

See this PSU 101:
http://forumz.tomshardware.com/har [...] 98276.html

Top Tier PSU:
http://www.xtremesystems.org/forum [...] p?t=108088

Exhaustive PSU review:
http://forumz.tomshardware.com/har [...] 10122.html

I've tried remounting numerous times and resetting the CMOS to no avail, has been suggested to update the mobo BIOS but I'm already on f5 do don't know if it's gonna help. Think I'm gonna buy a more powerful PSU, try that, if it still doesn't work I might just have to get a 7950GT instead (although I really don't want to as I hear the 1950xt is quite a bit better.