Whether you want to believe it or not, it is NOT wise to unplug/plug devices when the system is powered up. The few notable exceptions are USB and possibly FireWire devices that were designed for that purpose.

Yes, I have been guilty of the same behavior in the past, but have learned my lessons well !!! I may not have "blown" the motherboard, but I have had occasion to "blow-out" the serial/parallel controllers, the PCI controllers, the IDE controllers on motherboards and even video display adaptors due to the "haste makes waste" syndrome. Some of the previous problems can be overcome by popping in an IDE controller (unfortunately into an ISA slot) or another video card just to partially revive a system.

I make no excuses for past behavior. Sometimes the lesson can be quite costly if the person doing the job destroys some vital component on a friend's, co-worker's or customer's system.