Aside from perhaps the performance of graphic-intensive applications (such as games and video editing suites) there are few visual indicators for an overheating video card. That means that unless you’re using those high stress applications it can be almost impossible to be really sure if there is a problem with your card, and whether or not it’s actually overheating. Luckily, the solution isn’t too difficult.
Start by download the application known as Everest. There are only commercial editions officially available these days, but if you type Everest Free Edition 2.20 in to Google then you should be able to find somewhere to download the original freeware version.
Once downloaded and installed find the tab that relates to the temperature of your hardware components (there’s not too many menu items so it should be fairly easy to find). Then you’ll simply need to find the specific component that is your video card, and the associated temperature.
But there’s a problem
How do you actually tell if you video card is overheating? There is no “average” graphics card temperature, because they vary so wildly and can handle varying different levels of heat. The answer is actually quite simple:
Go to an online computer forum (hardforum.com is a good choice) and simply post about your graphics card and ask what temperature it should be. The answers will still vary somewhat, but if you notice that your card’s temperature is oddly high compared to the responses, then you’ve probably got an overheating problem.