Blackened 24 pin connector. Scary

This gave me a scare but I recently noticed a few crashes and weird instances where my old 9800gt card would stop outputting video when playing intensive games. The monitor would suddenly notify me that there was no signal on its HDMI input mid-game. I'd reboot the PC and it wouldn't output anything from the card. I'd then turn it off and wait for a few hours. I'd turn it back on and it would work fine for a few minutes but stop outputting video after a while.

This would repeat and I was clueless as to what was causing the problems. Then, I pulled out 24 pin motherboard power connector and saw that two pins on the connector were black. The plastic surrounding the pins was burnt as well. Now if I remove my video card and use the onboard graphics on my intel mobo, the system appears to be stable.

What should I replace here? The PSU or mobo? Or both? The PSU btw is one I got bundled with the case and doesn't seem too reliable. It's also quite old (5-6 years old). The motherboard is a socket 775 DG41CN Intel board. I'll post pictures in a while when I get back from work.

I guess I'll have to. Just hope there's no damage to the motherboard.

yep, cheap power cables can do that. A few weeks ago I installed a cheap cpu 4pin cpu power extension cable, it melted and the copper was showing.