Graphics card possibly broken, not sure how to check

Here's my situation.

I have had this rig for about 4 years, so it's not unlikely the card is fried but here's my dilemma.

I just reinstalled windows 7 so I could play Star Wars: The old republic.

Everything was working fine until today I logged in and suddenly when playing the game became unplayable due to low fps. I was playing very smoothly on max settings before this for a week.

System specs are:

WIndows 7 ultimate
Radeon HD 4870
4 GB Corsair DDR2
Abit I35 Pro MB
500 GB HDD

Even on the game when I put it to lowest settings it doesn't increase the FPS.

How can I test it to find out what the problem is or even to find out if it's broken?

I plan to reinstall windows as a last resort.

I also did a stress test on Counter Strike: Source not long ago, and got 280 FPS on everything maxed, so I'm going to try that again and see what my results are. I got an average of 12 FPS on furmark with 1280/1024 full screen which gave me an overall score of 770. The website scores my card way above that so I'm not sure what to do.

I have updated drivers.

Thanks

With that many miles on it, I would just change out now... you will quickly see that nothing lasts for ever.

Did you install the latest drivers from AMD.com? You can also try to install the Application profiles. It's available on the same page.

Try your video card in a friend's machine. Four years is a LOT of time on a Radeon HD 4870... if used very often... bit only you can assess over use. Look for a new card online on the 23 or 24, or buy the week after Christmas.