Well a few more ideas,
It could be that your power supply has blown a fuse or burnt out completey. If you have a multi meter I'd check to make sure that the posative and negative leads actually have power.
When you plug the power into the motherboard do you hear anything do any fans get a bit of power and spin up for a very short time and then stop?
If it works with the old no name PSU its either going to be the power supply or the motherboard that has the problem.
Hope this helps