here is the best solution, if you have a gpu that is having issues that means you've got an underlying problem somewhere which should be checked out, if you rig CANNOT RUN for 30+ days without any problems there's an issue you need to fix and its as simple as that, stop trying to use some script or little program to reboot the rig when clearly you've got a problem somewhere. the one thing everyone posted on this thread has FAILED to even mention.
a good running rig can run for months with no problems what so ever, the fact you are having issues shows there's a problem somewhere