I have a 7850 and it never did that
also speaking of videocards what is the best thermal paste for them
Any thermal paste will do, however I reccomend IC Diamond high density. Highest quality thermal paste, using synthetic diamond.
http://www.innovationcooling.com/overview.htmthermal paste ... for video cards ...
what?
Under the heatsink of a video card, it's essentially very similar to a motherboard with a CPU. By default there is regular (usually high quality) thermal paste on the heatsink and Graphics Processing Unit (GPU) chip. The Titan for example:

Some people find that opening up their Graphics Card and cleaning off/replacing the thermal paste with something like Arctic Silver 5 High Density, you'll get better temperatures. Theoretically you will.