nVidia GeForce GTX 660 TI OC can't get past splash BIOS

[xprongs]

Hey guys, I've just recently built a computer using the QUO custom mATX motherboard alongside MultiBeast by tonymacx86 to have a desktop capable of running Windows and OS X. I was using a friends' old Gigabyte 6850 OC GPU but decided I needed an upgrade, and bought a nVidia GeForce GTX 660 TI OC.

I went through all the steps of unplugging the PSU, uninstalling old drivers, and installing the new GPU but whenever the unit is connected, regardless of where the DVI cable is plugged into, the computer takes ~2-3 minutes to get past the splash BIOS, at which point it shows a flashing underscore and then goes black. All fans etc. continue to run but there is no visual output.

Here's the rig:
Intel i7 3770
Corsair 4gb DDR3 x2
Z77MX-QUO-AOS motherboard (modified Gigabyte Z77MX)
LG Bluray DVD Reader/writer
Samsung 120gb 840 Evo SSD x2
Seagate 1tb HDD
Corsair cx500m

All mounted in a modified Mac G5 case.

It all works perfectly, except for when I try and use the new GPU.

Any ideas?

 

[potpolima]

update bios and check the cables...try using hdmi or vga interface

 

[xprongs]

Updated BIOS and tried older versions. The monitor only has a DVI input.

I just tried using the old GPU, the AMD RADEON 6850 and it works fine, which means it's not a problem with the BIOS or any other settings we're running. Also can't be an issue with the other hardware.

Am I wrong in suggesting it's potentially a faulty GPU?

 

[Adroid]

Couple more suggestions/ideas"

*Make sure you are feeding enough power to the graphics card. Are you running the right power from PSU to the GPU?
*Not sure if that PSU gives off enough juice to support your GPU. Unfortunately, I'm too lazy to research it for you atm. Google both your PSU and your GPU.
*Put the other graphics card in, boot to windows, and adjust your resolution to something lower. Then put the new GPU in and try to boot up.