Hi Whirly. Apparently my problem was a corrupt GPU profile file for SL that wouldn't delete itself and managed to fix it by removing temporary files and several tries using the legacy Catalyst menu under Crimson's Additional Settings in Preferences (Power menu). Though SL is only managing High on my GPU now, might be to do with the network lag I had yesterday, however. Not sure if the corruption was caused by the viewer or drivers / auto-updates as I didn't touch anything. I know SL did black screen on me twice and tell me one of my GPUs had crashed (can't remember which). Either way, I hope this helps others who had the issue as I know a few who did, too, just with SL Viewer. Thanks.
EDIT: My audio is making a spitting noise when I play SL and a music player when running AMD, not sure if to make a new thread or if this will be seen here. Not sure how to fix it. Lag meter has my client in yellow sometimes.