Asus P8Z68-V LX not detecting graphics card

Let's start with what I got (just recently built):

Corsair TX 750w psu
asus P8Z68-V LX motherboard
intel 2500k
geforce 460 gtx

So I put the computer together yesterday and everything seems to be working great except my 460 gtx is not detected by windows or the bios. I checked to make sure the fans on the graphics card are running and they are (not at full speed either). I tried updating the bios to the most recent version, turning lucid on/off, set initiate graphics to PCI E, etc. etc. and cannot get it to come up.

Eventually I remove the graphics card from the case, make sure the power cables (2 6 pin pci e cables) are plugged in tight and install the card back in. Finally my 460 gtx works! I must of spoke too soon though because as soon as I connected both my monitors to the graphics card, it once again was not detected.

I know this graphics card works fine because it was in my old system. It was working for a good 20 minutes in my new rig before I plugged both monitors in and tried to stop using onboard graphics. Any ideas what this could be? I really hope I'm missing something that can fix this so I do not have to return the motherboard :banghead:

As always, any help is much appreciated!