So um, I found the real problem.
The power supply wasn't too small, apparently my earlier troubleshooting was partly flawed. Something went wrong with this component on the video card, and it was causing a short circuit. It completely fused itself, burnt part of the circuit board, and scorched some neighboring components.
I was very sad when I figured this out, cause that video card would be very expensive to replace. (I've already hosed my warranty by removing the heatsink, watercooling, and overclocking it.) Undaunted I grabbed my pliers, tore the offending component off the board, and plugged the card back in.
Apparently it was an appendix; the video card (so far) works fine. - Who knew!?
Although I really would like to know what kind of a component it is. Maybe I can order a new one and solder it on to the board. I'm assuming it's some kind of a power supply component for the video card that overheated and progressively shorted itself out over a period of time. If you want to help me identify it here are some more pictures.