Hello, I have a Dimension 8400 which the motherboard is bad.  I had contacted Dell to buy a replacement board. I have a U7077.  They had said the board is discontinued.  Is there a different model board that will interchange with the U7077?  I've been lookin at some on ebay, and not sure what to do yet.  I'd like to buy a new board, but am only seeing used U7077's.  Thanks for any help anyone can provide.