Artifacts

hey guys I need help.  I just tried overclocking my 7600gt using ntune.  I clicked on find optimal settings and it put it on 622 and 855.  So I clicked apply .  I then started up fear and I'm seeing a alot of artifacts.  I then went back into ntune to try and set it back to normal settings, but every time I lower the clock speeds it  says 'GPU test failed'.  What can I do to get it set back to normal settings again?  Should I try using another over clocking software?  Someone please help.

Well, I just restarted my computer and it went back to factory settings.  Am I always supposed to restart after overclocking?  lol sorry I'm kinda new at this.

Well, I just restarted my computer and it went back to factory settings. Am I always supposed to restart after overclocking? lol sorry I'm kinda new at this.

jorbo76