I did damage a motherboard though, changing the clock crystal on an old 386 system. I think I was going from 20 Mhz to 25.
I managed to brick an i5 4670k about 6 months ago. If I remember correctly, I was trying to use ASUS AISuite extreme OC. Even after resetting the CMOS, I could not get the PC to boot up. Exchanged it with an i7 4770k and everything else was intact.
What kind of OC settings did you use? Voltage?