Re: NVIDIA/Linux setup for VirtualGL on node with no monitor
That may be the clue. The M2070Q can be either a 3D Controller, or a VGA device, depending on what VBIOS is flashed on the card.
Since your xorg.conf does not specify the BusID of the device, I think X is getting confused and picking the onboard ATI device instead.
Can you add:
To your Device section in xorg.conf and see if that helps?