The issue is caused by Operating System limitations as well as NVIDIA driver limitations on Windows Vista/Windows 7 for applications running as a Windows service.
By design MDCS workers, when managed by Job Manager on Windows, are run as a service. By design all Windows services are attached to Session 0 Windows Desktop. However, the actual rendered user desktop is attached to a different interactive Session. To prevent malicious code inside of services running on the system from taking over the user desktop, all programs running as a Windows service are prohibited from accessing the user desktop session, and writing to the graphics card associated with the user desktop. Furthermore when using default Windows NVIDIA drivers, even cards which are currently not attached to a user display are by default not accessible to programs running as a service.
To work around this issue NVIDIA released a special driver set called TCC (Tesla Compute Cluster), which bypasses the Windows Vista/Windows 7 graphics driver restrictions. When run under TCC drivers compatible devices not attached to a display become visible to services. However, these driver are not graphics drivers and are unable to render a display.
Detailed description of this issue can be found at:
The list of NVIDIA GPUs that are supported by TCC can be located in Appendix B of NVIDIA Tesla, Quaddro driver release notes:
It is recommended that when running under Job Manager on Windows that you install the TCC drivers, and only use supported (Tesla) cards for GPU computations.