What version of FOG?
This is just a guess, but, because imaging works for you with other systems, that particular motherboard might not be supported by the current kernel / inits that you have.
You could try other kernels… newer ones… older ones…
If you find one that works, let us know so we can update our hardware lists:
https://wiki.fogproject.org/wiki/index.php/WorkingDevices
https://wiki.fogproject.org/wiki/index.php/ProblematicDevices