I have a 3.5mm extension hooked up to the rear. In the other side I plug/unplug my headset/sound system. When this fail, I just go to buy another 3.5mm extension. On this way, connectors on rear don't suffer.
+1
BTW, a decent 500W psu could easily handle a i7 + 680. So you can just find out a good psu and later can upgrade video card to high end.
PD: See my specs and psu I'm using.
A ram module not working properly maybe cause that problem. Try memtest86+
If you can't, so remove two slots and try several configs (ex. modules A, B, C & D: AB, BC, CD, ...)