Hi Gordan,
I wanted to let you know that today I decided to have a try for my GTX 680. Gigabite GTX 680 2048 MB GDDR5.
I know that this particular card could be hard-moded to GRID K2 so VGA passthrough could work.
Following instructions found on http://www.eevblog.com/forum/chat/hacking-nvidia-cards-into-their-professional-counterparts/420/ I just removed two resistors.
Here is a screenshot taken from a VM (Ubuntu 12.04 32 bits) with more 8GB of RAM.
http://www.eevblog.com/forum/chat/hacking-nvidia-cards-into-their-professional-counterparts/420/
I did the test on another VM (Windows 7 64 bits). I was able to play games, shutdown the VM, restart the VM without restarting the dom0.
I am very impressed. Restarting domU (Linux or Windows) without restarting the dom0 is very
impressive.
I just added a youtube video about my tests for my hard-moded card
http://youtu.be/L1RoOx8wC7A
Apologies I am French so I am speaking in French in the video. Just to show that it works perfectly.
Kind regards.