This sounds just like the problem I'm having (check my thread for more details).
After resetting the CMOS the same problem occurs. You mentioned that you get no POST beep, have you checked that the speaker is plugged into the motherboard? It'd be a great help if you could clear that up as I have an Antec 900 which doesn't include a speaker, so it's not possible for me to tell if my system is posting at all.
I'm going to continue my 3rd rebuild of the system a little later, I'll post my results straight after.
After resetting the CMOS the same problem occurs. You mentioned that you get no POST beep, have you checked that the speaker is plugged into the motherboard? It'd be a great help if you could clear that up as I have an Antec 900 which doesn't include a speaker, so it's not possible for me to tell if my system is posting at all.
I'm going to continue my 3rd rebuild of the system a little later, I'll post my results straight after.