In article , says...

First thing I would try is a LiveCD linux distro, doesn't really matter
which one (I like Ubuntu for this), and see if that boots without error.

Tried an Ubuntu LiveCD first in my own machine and it worked well but it
would not boot in the suspect machine. I get a screen with two icons at
the bottom but nothing else except a flashing cursor in the top left
corner, picture here (just click on the photos to zoom in)
http://s137.photobucket.com/albums/q...ackard%20Bell/

Had a couple of problems before with supposed quad core capable
motherboards that actually weren't...
Does this motherboard have the exact bios and hardware revision of the
faulty one? ie does it properly support that CPU?
Do you have the bios settings set correctly?

Is the PSU up to the job? I know you said it is, but what is the rating
of the 12v rail and is it clean...

Yes, to all of the above.