Gigabyte GA-EP43T-USB3 power-on issue

[dissemble2discover]

About a week ago, my custom desktop comptuer started to experience "bearing" from the power supply fan area. I also was looking into install one of my old graphics card - an amd radeon 6670 - but realized that my Power supply was also lacking the amount of wattage to even consider the graphics card to be installed in my system.

I purchased a 550-Watt power supply, went to install it into the system while removing the old, 300-Watt power supply.

When I connected everything back up, the system would no longer boot. I tried swapping back the power supplies again to see if it was the 550-Watt PSU that came to me DoA. It didn't power on with the older 300-Watt PSU either, and nothing else was moved but the power supplies themselves.

I made sure all connections were connected correcting (cpu fan and 4 pin power connector, ATXV12 connector) and still no avail.

It powers on with all fans except the CPU fan spinning, then 3 seconds later it shuts off. It does this twice before it stays off completely.

Is there something that I am doing wrong or ignoring?

I have:
- MB: Gigabyte GA-EP43T-USB3
- Intel Core 2 duo processor
- 500-Watt power supply
- 2x 2GB ram sticks

 

[smorizio]

Check that the mb not hitting the mb tray and shorting out. Look under the mb for dust shorts and drop screws. Checked for pinched or sliced fan wires.
You may have to clear CMOS if there was a power issue. You may have to bread board the mb outside the case with just one ram stick to see if it powers on and gives you a CMOS beep code failure for missing video card.

 

[dissemble2discover]

Check that the mb not hitting the mb tray and shorting out. Look under the mb for dust shorts and drop screws. Checked for pinched or sliced fan wires.
You may have to clear CMOS if there was a power issue. You may have to bread board the mb outside the case with just one ram stick to see if it powers on and gives you a CMOS beep code failure for missing video card.

Thanks,

I will try all of those suggestions and report back.
It's weird that this issue only happens when I have the 4-pin CPU connector plugged in. And without it, it stays on just fine. But I will check the back of the board for shorts.

Here's a video of to show what's visually happening too:
Video 1