just today, i would see flicker lines on my screen,
is that a sign of overheating? should i stop my games immdiately and try to buy a thermal paste the next day and attempt to replace
Idk bout those flicker lines. The fact that you mentioned 90 degs on a DESKTOP is already clear red flags for bad overheating. Under gaming load a normal desktop hits at max 70+ degrees.
Definitely stop all gaming/any forms of heavy load on the computer. Extended 90+ degrees on the CPU and GPU is very harmful to both.
1) How old is your system? And when was the last time u did a repaste? If your answer to both is years ago, chances are your system desperately needs a repaste. If you wanna ownself repaste, make sure to watch some youtube vids and read up online to get an idea of how to do it properly.
2) After repaste, run a stress test/or simply game and check temps. If you're hitting 80+ degs, means your system is still overheating. Now check the fans(which i assume if you answered "old as hell" to 1) means your fans are also dying) so, check if the fans spin up properly, and the airflow is in the right direction. Buy some good coolers to 'refresh' your system. Hyper 212 Evo is not bad.