akhasheni thanks for the mention!
Here's a screen shot of one of the Custom WMI monitors, that I have configured for our NVidia cards. I hope it helps.
As aLTeReGo mentioned, WMIexplorer is the tool to use, as it gives much clearer results and allows WQL statements to be tested.
I can post up the exported NVidia Template that I created if you'd like, hopefully it will work.
Oh I should mention, you'll need the NVidia NVWMI loaded, if your graphics cards support it.