2 GTX 760s in motherboard, can I use bottom card only?

[Ashihtaka]

I currently only have 2 pcie 6 pin power cables. This is enough to run 1 gtx 760.
The problem is only my top 760 seems to be working. When I plug it in, my computer runs and the display shows. However if I plug the 2x6 pins into my bottom 760 (by bottom i mean the lower PCIe slot in my mobo), the computer runs but no display shows on the monitor.

I want to know if the bottom 760 is defective, or do cards on the bottom not work if the top is in the motherboard (even though not connected to 2x6pin power).

PS. I'm running a watercooling loop, so it will be very difficult to switch the two 760s to test this.
If no one knows the answer, then that will be my only hope, but I hope someone has experience with this.

 

[photonboy]

I doubt the card is defective.

If you want to test the 2nd card, simply shut down the computer, remove the first card and have the 2nd card attached to the power supply.

I'm not sure exactly what's going on but it's most likely an issue with you not having the power connected correctly.

*Why do you have two GTX760's installed without the Power Supply to run them? You do realize you need a Power Supply that can supply 4x6-pin connections so both cards have power?

Summary:
Get a correct power supply and things should work properly.