I’ve actually fixed a few PCs in the past by opening them up and cleaning them out. Enough dust can accumulate that fans will no longer spin fast enough and other components will start to overheat from their new fuzzy blankets. A few trips outside with a can of compressed air and all is working again. Make sure you are standing upwind. It’s embarrassing when your neighbor looks out the window and sees you prancing around the front yard waving your arms around like there is an invisible swarm of bees following you.