I've never opened a superslim, but I've opened many 360s. One thing that can cause them to overheat is if the heatsinks aren't making contact with the chips. I do own a superslim that I got for free, and I've never had it overheat. I even beat several tales of games on it, so long games, and having PSN+, I have it set to send saves to cloud and sync trophies at around 8 p.m. every day. I've never changed the thermal paste.