There are many things you could do from a hardware perspective:
Locate your video card fan and clean it with a vacuum cleaner. Offer more air circulation to the external vents at the back of your computer by using risers. Find out if your graphics card has an open-air vent near where heat exhausts (most do). Position a desk or shelf in front of the opening. This can create airflow through which cool air flows–you may find that one side then runs cooler than the other, so think about rotating it periodically to keep temperatures even throughout its lifetime.
For software related issues, sometimes they just need to be cleaned manually too:
- Close down any background programs
- Maintain temperature by shutting down the computer when not in use, and periodically restart it to clear out the cache
- Pop in a temperature monitor to make sure your PC isn’t overheating
- Ensure the temperature limit is not set too low
Of course, there are other things you can do to make sure your computer doesn’t heat up too much; make sure it has good ventilation and stays clean inside.