that burning smell!

[Frozennova]

I've just RMA'd that exact board. Completely different reason though, and can say its fine running an overclocked Quad as I had a Phenom II X4 @ 4ghz without issue

 

[Reality|Bites]

I'd say either dust in the PSU or if you're using molex splitters(sometimes the wires are really thin) one could have fried and split starting a small fire which stopped when you cut the power. Happened to me one time.

 

[powelly]

The R50 component is a ferrite choke.
(see: http://www.hardwaresecrets.com/arti...e-Motherboard-Voltage-Regulator-Circuit/616/1)

MOSFETs have the tendency to heat up when quite a lot of volts are being passed through them without cooling (eg. passive heatsink). Was the vcore left on auto when you unlocked to quad? That could explain the problem as too much vcore is required for the unlock. (probably why it was binned in the first place)

i assume this was the case, all i had to do was press 4 on start up because of asus acc