That card always ran hot, and Furmark can push it very hard indeed.
It would definitely be a good idea to pop down to your local computer store, get a can of 'compressed air' and give the card a clean out.
If you're unsure it should be done like this
You'll need: A can of compressed air, a small brush or some cotton buds, a piece of cardboard large enough the lay the video card on, a dry day.
Power down the system and remove the power lead.
Remove the card, try to hold it by the edges and do not touch the gold contacts.
Lay the card on the cardboard and clean the fan blades with the cotton buds/brush.
Take the card and can of gas outside and use it to clean to internal heatsink fins by blowing BACKWARDS, into the exhaust or towards the fan/s.
Do not blow directly onto the fan/s or you risk overspeeding them and use short bursts.
If you accidentally touch the contacts they can be cleaned by GENTLY using a pen eraser followed by a short burst of air.
If you are bothered with static, keep a part of you in contact with a earthed surface like a wall or radiator.