My GPU has started overheating, hitting 85-90 C and throttling down. I pulled the heat sink off, which was full of lint, cleaned the contacts, re-applied The Chill Factor thermal grease, spread with a card for a nice thin layer, screwed the heat sink back in in number order, retested, and I'm still getting 85-90 C temps. CPU is doing great, at about 40 C under gaming load. Fans on full, of course.
What to do?