Help! Video Card or Motherboard Problem?

Hey everyone, I am new to the forum and I need your help.

I want to include a back story so that you may be able to help me if I overlooked something. If you want to see the problem summary scroll down to the end.

I just purchased an upgraded video card (NVIDIA gtx 260) for my custom built system and it has given me nothing but trouble.

At first whenever the video card would start rendering some graphics (everything from nvidia logo in the control panel, to Warcraft) the computer would blue screen. I had the bright idea that it was my PSU since it was just meeting the wattage requirements but not the Amps for the 12v rail.

Long story short I get my new PSU and install it, and to my blood curdling amazement it was still blue screening.

So I went after the next culprit my operating system/drivers setup. XP-64 bit has given me so many driver problems before it is hard to believe that I didn't reach this conclusion first. So I install my windows 7 Beta on another hardrive and proceeded accordingly... and everything was working just fine.

So I decided that I would play some Warcraft but I had to redownload the client to this harddrive... which takes a few hours. So, I go to bed for the night and when I come back to the computer in the morning the computer is not on and it will not start back up.

I thought it was the psu so I plugged in my spare and ruled that out. I swapped the videocard with the old one and the computer booted up no problem... so I then put the new video card in and FORGET to plugin the two required PCI-E 6pins... and viola it worked.

So here is the problem:
The NVIDIA gtx 260 is causing my computer to not boot(the led fans light up for about 1 sec). However, whenever I have the two PCI-E 6 pins detached it boots. So is this a problem with my motherboard or with the videocard?

I am leaning towards RMA'ing the video card and starting from there

I appreciate any advice you can give me. 1000 cool points to the answerer.

What are the exact model numbers of the video card, power supply (new one) and mother board?

PSU: CORSAIR CMPSU-650TX 650W
Video Card: MSI N260GTX-T2D896-OCv2 GeForce GTX 260
Mobo: GIGABYTE GA-P35-DS3L

Well, that power supply exceeds the minimum requirements... I agree that this is an RMA candidate (the video card).

For the record-- the card requires 12vdc @ 36a via 2 x 6-pin connectors. The PSU provides up to 52a on the single 12vdc rail and has 2 x PCI-e 6+2 connectors.

Personally, I like to have a PSU with a dedicated PCI-e/Video card rail, but this PSU does meet spec.

I agree, but for this build the PSU exceeded the requirements and was a steal of a price.

So the video card is the likely culprit, I can only hope that my rebate doesn't get messed up from the RMA.

If anyone else has any comments or suggestions leave them for me, in case the replacement video card does not solve my problems.