The x86 MBP was stuck in a vicious cycle of getting overheated, running the fan all the time at high speed, sucking up enormous amounts of cat hair, and jamming up the motherboard and cooling vents: the hotter it got, the faster the fans ran, the more cat hair it sucked up, the worse the cooling and more snuggly warm the insides got, the more attractive it was for the cat to sleep next to.