You can see what stats are available through WMI with the query Select * FROM win32_videocontroller and the WMI Tester. Once you find the information you are looking for, you could set up a custom WMI sensor or you can use the perfomance counter stats from the server with a custom perf counter sensor.
Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.