Something killing Logic Boards?

I have the listed early 2009 Imac 2.66...

They have a built in video GPU and are a real pain in the you know what... However I need some troubleshooting help.

I had a unit with a broken screen that I repaired, about 10 days later the screen started doing the inverse green flashing. At post, the white background looked like greenish and pinkish snow and the apple icon was a snowy green. The desktop was all kinds of hypnotic colors...

I ordered a new board (manufacture refurb) from Asendtech.com that included a CPU and heat sink.

Installed and it seemed to be worked fine.. THEN PROBLEM 1

At startup with nothing plugged in. I would get a USB power surge error. Nothing was plugged into the USB slots and it would still pop up. It also would always tell me the clock was set before January 1st, 2008. But the clock had already updated since it had wireless connection. I did the following problem solving.

- Replaced the board battery

- Removed Bluetooth/extreme card

Still got the errors.

I ran the AHT and it came with an error on the 4MOT/... ODD-4382. Replacing the Temp sensor cable on the superdrive made that go away.... No other errors found.

THEN!!!! It did the SNOWY screen with the SNOWY GREEN APPLE ICON. on the restart!

WTF JUST HAPPENED AGAIN?