Did you try a new PSU (or a known good one)? Maybe it can't supply the power needed.
I'm sure your reset the BIOS, no hope ?
Try a new videocard, and if it doesn't help,
maybe you got some bulging capacitors, did you check? In that case maybe just the MoBo is dead.
Plug some headphones into the rear green jack and listen to the BIOS REPORTER, maybe the voice will tell you something (hepefully).
My money is on the dead mobo.