That's really weird. To say that it is the Antec PSU is not correct as you tried with the Enermax but it has the same problem. To say that it is the motherboard is also not correct as your old PSU is working fine.

Maybe it is compatibility problem? I'm not too sure.....

Just a question, if your old PSU is working fine, why change it? Remember that software readings of voltages are notoriously inaccurate. As the saying goes - why fix it when it ain't broken......