What it says on the tin. (Click for embiggened version.)
The trace appears to be the 3.3V voltage line between the ATX connector (pin 13) and the DDR2 RAM slots on a Micro-ATX motherboard. (Edit: DDR2 does not run at 3.3V, so either it’s going somewhere else or I have no idea what’s going on–probably the latter.) I upgraded the RAM from 2x1GB to 2x2GB, but apparently in the process I also upgraded from “working-but-wonky backup server” to “dead motherboard with a side of magic smoke”.
I’ve never seen anything like it. I’ve put disassembled and put together hundreds of computers and the worst damage I’ve ever caused is a broken header pin. The only thing I can think of is the RAM sticks (which are tiny half-height sticks) may have been damaged when I pulled them from another computer, or when I installed them. One of them has a pin that is discolored and raised away from the module. Unfortunately, I don’t know if it was that way before or after the trace fried.
I’m keeping the motherboard for soldering practice.
Anybody seen anything like this before?