Motherboard or PSU problem?

OK so my problem can be replicated two ways... first is that upon SAVING AND EXITING BIOS about 80% of the time it fails to post... no beep no picture... I have to completely switch off teh power supply and reboot then it works fine (and settings do save).
Second is upon resuming from suspend or hibernation. I get the exact same symptoms... I hear fans spin, hard drives powering up but no beep no screen. Oddly once I clear the power supply again it will resume from hibernation mode (obviously not suspend as I have cleared the memory at this point).

I have eliminated memory as a problem as it has done it with two vendors on multiple settings in multiple arrangements.
It also is not my video card because I have tried my Radeon 4860 and a cheap GeForce.
My approach is very minimal as I have almost nothing plugged in to the comp (USB mouse and PS2 keyboard) and no expansion cards beyond the vid card.
Also I have the newest Bios update... doesn't seem to be a widespread problem on the Asus forums.

I have an Enermax 720w Modular PS and an Asus P6X58D premium. I have messed with every possible power setting in bios and nothing worked. Any ideas? I am thinking of RMAing the motherboard first and then the power supply (possibly at the same time to make sure I don't have excessive down time). This is really frustrating.

Is there any chance it could be something as stupid as the CMOS batter or a jumper? It seems to me like it is hanging due to some sort of power issue because when I manually reset the PSU it works.

There's a good chance that your PSU has a fault in the standby circuits. I'd RMA the PSU first.

Well before RMAing the PS I stopped being lazy and tried an old Raidmax PSU I had (I know they are horrible hence why I don't use it)... well it is doing the EXACT same thing. I am gonna just send the board back as I am now under the impression that it isn't the PSU.