This is not my first post and it happened over two years ago when i worked somewhere else as the main support guy at a research facility.

Long story short I had the long-time-task to fix all computers that did not complete a TSM backup in a while. While most computers did not exist anymore or were simply turned off, quite a few had problems connecting to the control server.

So I was on investigation again to find myself in a dusty lab-storage room with around a dozen of old Optiplex 740s, 745s and 760s still running Windows XP and Windows 7 at the time most computers were already on Windows 10.

Most of them were turned on and had problems accessing the control server to make a backup. Not this one. This one 740 was turned off. Turned off for quite some time. I connected the AC and was surprised not to die because this Optiplex exploded the moment i pushed the power on button. Needless to say i ticked this one of the list because the client got replaced.

TLDR: turned on a dusty computer and it exploded on the spot.