How much resources does game use when minimized?

Assuming I use full screen and I press the windows key to minimize the game, how much resources does the game use while minimized? Particularly is the graphics card processing the game and is the RAM working to support the game? Or is the game in a low state?

I remember with my old computer I would hear a fan blasting while playing the game, and it would stop when I minimized it, leading me to believe there is a difference.