I still have two never used motherboards in my cupboard from when i'm messed something up but got fixed before replacements arrived and needed.
First time on my core2duo system I dropped a thumb screw onto the motherboard and fried a chip, forget why I was doing this and being lazy at the time,
So I sent it back to Gigabyte for repair which cost £20, Before I had thought about emailing them just on the of chance that they would entertain a 3 year old board I bought an Asus replacement.
I install the Asus board but it was a total PITA to get stable, one day I left it on while I went to work (slow dl speeds at the time) and when I came back the board was dead, So I email the shop and got a replacement for the Asus board, but while waiting for that to come back the gigabyte board came back
So the replacement Asus board has never been used.
2nd time was when getting into watercooling and my res spat some fluid onto the bottom right connectors and shorted the system, The GF offered to buy me a new one for my bday, but I wanted the same board and as it was so old I had to buy it from a random shop in Germany lol, By the time it had arrived the board
had dried out and ended up turning it self on at random so that board has never been opened or used.
TLDR: I'm bored