My most annoying oc was a Celeron 2. My motherboard did not apply custom voltages until after post, and it would not post at the 850 MHz I was running it at with stock voltage. I took one of those old small dc motors and unwound some of the wire from it to short the pins to up the requested voltage to something that would run long enough that the system would post and apply the stable voltage. Ran like a champ until I retired it.
edit: Why I wrapped the pins instead of using the normal pin mod procedure of just jumpering the holes in the socket, I cannot remember. Let me tell you though, wrapping a tiny, tiny strand of wire around a specific 3 processor pins and then tying it so that it would be stable was not an easy process.