Have you cleaned the dust out lately?
How is your wire management?
I had an overheating issue myself. I looked into it today and found a lot of dust in my heat-sinks and on my fans. I removed the big components (GPU, HDD, PSU), dusted out my computer, redid wire management, and hooked it all back up. Runs ~10c cooler now. That's after I put one of the computer covers back on too.