Video card temperature on vista?

My nvidia 8500gt ddr3 oc edition gets 59c. on start up and the maximum i got in 12hrs straight is 63c. When i overclocked it one step forward it shows 56-57c. Why lower? i expect that it will get hotter|||It's going to be lower if your not using it because it doesn't want to overheat. Usually though when you start up your computer or are going to play a game the temperature will rise.