I purchased an Apple mini circa 2009 for $10.00. 2mb memory and mechanical HD. It was painfully slow so I upgraded to 8mb ram and a SSD. So when I took the mini apart, all kinds of hardware fell out! After looking around, I found out that the CPU heat sink had been secured with plastic pins and springs. The pins had broken and of course whatever they use for thermal CPU/heat sink contact was hard as a rock. The insides was stuffed with dust and dirt. I am surprised the unit worked at all without thermal shutdown.
So I blew out the debris, scraped off the old heat sink compound and replaced it with some fresh compound, secured the heat sink with 4-40 screws and put the mini back together. WOW! it is like a whole new machine. I just might keep it!
The unit will only officially run El Capitan version of OSX. So I went to the Apple store to put a fresh install on the mini and no El Capitan! WTF! So instead of first asking the interwebs on how to install El Capitan I searched for a dmg of it and found a few but was unable to get them to install. So finally I asked Google which pointed me back to Apple. Apple has the answer but you have to ask to find it! You have to download and install a whole new Apple OSX installer. OMG!
Some people might like the Apple way but I cannot say the same. Thank goodness we have choices.