Main computer back online

It was a mainboard failure, but I think I've identified the actual culprit. About a week ago I put in a nice, cheap USB hub. 10 ports. It seemed to work well. However, the manufacturer decided to save 3 cents by installing a zero-ohm resistor in the "D0" position (should be a diode). I discovered this today after the following escapade. This diode is intended to prevent power from backfeeding into the computer from the hub. Without it there, it was freaking out the power supply and I think eventually it probably caused enough oscillation on the power bus to blow something on the mainboard.

Due to the swapping around, the chassis for this machine didn't have a power supply so I just dropped in the new one I got today (I like to have a spare around). I think this power supply is smart enough to detect shenanigans and refuse to play. I was careful to test proper power-up several times during assembly, but when I plugged everything in, it refused to power up. I quickly determined that the hub was the problem; with it unplugged, no problem.

The hub works very well otherwise, so I'll probably install a diode there and keep using it, but I certainly won't be buying any more of those (I was thinking about it since it's nice just having a huge pile of ports).

Oh, and since the new mainboard has a completely different chipset, I had to reinstall Windows; the old hard drive just got to "Starting Windows" and the specks started flying in for about 2 seconds and it flashed a blue screen and rebooted. At least Windows 7 installs pretty fast.