IF the graphic card was working without any issues before, what has changed?
IF you changed anything such as Overclocking, please run the system at default. Also you can test the graphic card inanother system to see if it is defective.
Are you using third party graphics controllers? Afterburner,Trixx,Asus,MSI,etc. disable or delete them as they can conflict with Wattman. before you delete or disable them, use their 'return all settings to default' function to undo any changes made. Do the same with Wattman.