Re: Improbable
That would seem to be a plausible scenario. If 12V ended up on a lower voltage rail, I could imagine the capacitors on the lower voltage rail going. Alternatively, if the computer was old enough, there would have been a negative supply that one could short a positive rail to.
This reminds me of an experience I had in the early 1980s. My group had acquired a memory expansion board for a Floating Point Systems array processor. Unknown to us, there were slightly different versions of this exact model that differed in the backplane power pin assignments. On being told by the sales guy that "you just plug it in - what's hard about that?" we did just that with seemingly catastrophic results - smoke and, on further investigation, melted PCB traces. Miraculously, we were able to revive it after improvising repairs for the burned traces - it seems that the large current flow that resulted when the negative bias supply on the memory chips became forward biased was distributed over a sufficiently large number of chips to avoid destroying them.
Biting the hand that feeds IT
