1. What OS?
2. What type of monitor?
I used to have a Savage 4 based card, it had graphics curruptions under Windows. There are no new drivers for it to fix problems, as S3's rights have been bought out three or four times. Last I checked Sonic Blue had them, and were kind enough to put drivers on there download page for it (and all are pre-XP drivers, though there are beta drivers on the net for XP and Savage cards).