Caches are not related to a videocard issue. Someone reading your post might think they are. That said, caches should only be emptied when they aren't browser related on a backed up system*:
Sometimes if you inadvertantly empty system and User library caches while they are being written you can actually cause them to get corrupted. Normally caches are there to speed your system. Isolating a hardware from a software problem, you can certainly test if caches make a difference or not.