One out of two graphics cards not detected

[hoopertrevor]

I am running two GPUs (also known as heterogeneous graphics). The purpose of me doing that was to have one run graphics while the other runs PhysX. I have a GTX 770 and a GTX 560 TI. They are both powered and plugged in; the fans are running. My power supply is either packing 750, 800, or 850 watts I cannot remember which. I've checked device manager and the GTX 560 TI isn't showing up at all.

[Geek-9pm]

Some detail needed.
Whit is PhysX ?
This?
https://en.wikipedia.org/wiki/PhysX

hysX is a proprietary realtime physics engine middleware SDK. PhysX was authored at NovodeX, an ETH Zurich spin-off. In 2004 NovodeX was acquired by Ageia, and in February 2008 Ageia was acquired by Nvidia.[1]
The term PhysX can also refer to the PPU expansion card designed by Ageia to accelerate PhysX-enabled video games.

I have no idea of what that is. 

[Calum]

What motherboard do you have?  And, what version of the Nvidia drivers do you have installed?