Could just be in need of a clean, dust and fur from pets will quickly clog the fairly small fins of the heatsink.
Pop down to your local computer store and get a can of 'compreesed air', tell them what you're doing, they'll know what you mean.
You'll also need a few cotton buds.
Remove the card and clean the fanblades using the cotton buds, be gentle and try not to hold the card by the circuit board.
Go outside and use the compressed air. Blow it INTO the EXHAUST of the cooler, or from the underside if its a dual fan cooler. Short blasts, fairly close to the cooler and if you can, lean against something metal and grounded to prevent the buildup of static.
Hello... Take off the side of your computer panel, Does the temperature drop with fresh outside air? maybe you need another case fan?
Inspect your Heatsink on your Video card, I have seen improper mounting to the GPU's, because of capacitors touching the Heatsink.
Take off your heat sink and fan, and inspect/re-apply thermal paste, due too a workers Haste.