What does this error mean?

[manveruppd]

Found it in the Event Viewer under System, says it happened a few minutes ago, when the computer was doing nothing much really, was reading an article in my browser with nothing running in the background.

Silent Running: rising temperature caused level transition: L2 -> L1

Anyone?

 

[manveruppd]

Card eh? Good, was worried he L2/L1 business had to do with the on-die cache in my CPU. Checked and it was indeed the graphics card, it had clocked down to default from my overclocked settings. Weird as the PC was idle at the time the error appeared, nothing was happening to stress the graphics card certainly. I'm on the 84.21 Forceware, guess it's finally time to update.