Re: Macs typically have a longer usable life than Windows PCs ...
Heat killed 2 out of 2 iMacs our department had. The fans just got louder and louder and even taking it to bits and vacumming the thing out didn't help in the end. It was non recoverable and so a whole machine including the massive monitor was out. I'm sure we could have spent some time getting various bit repaired but time was too short. Swapped for a Mac mini and a standalone (non-Apple) monitor.
Eventually moved the Mac mini over to a mini PC.