Is the card artifacting lik crazy and makes playing impossible? If not, try opening your case , clean out all the dust and use an external fan to increase airflow. If that doesn't help, check the video card. Are there any capacitors that look warped or exploded? If so they are usually easy to replace, plenty of instructions online.

I've had similar problems in the past and burned through 2 video cards myself. The first card dtopped working because the capacitors literally exploded during game flow. I sounded like a gunshot. I replaced the caps and was good to go. The second card had a severe artifacting problem that got worse overtime. By underclocking the card, I made the issue go away.