You've got some serious airflow problems if your card is overheating and it's the only one in the case.

Download & run MSI Afterburner (found here) to check temps first.

If it's around or above 100*c, open up your case -- I imagine you must have a LOT of dust & whatnot clogging your intake vents to clean out. If there's still a problem, try keeping one side of the case completely open and buy some more case fans to mount inside it.