edit: Please tell me that is not 1.65V RAM. Your CPU's memory controller is designed for only 1.5V and 1.35V RAM.
I'd check for potential shorts to case (ultimately you may need to do a minimal external build).
I'd pull and reseat all wiring, especially the main power, auxiliary CPU power and GPU power. At the PSU too, if modular. Might switch wires if possible.
I suspect the PSU but several other things could cause this behavior.
When you first turn on a PC a lot of power is initially drawn upon; especially true in a high end system such as yours. This is bad for electronics but little can be done short of manufacturers installing some sort of slow power on the way chained SCSI drives used to do.
It could also be a initially failing "power good" signal.
The Power LED is the first case/drive/peripheral LED to turn on during boot. The fact that it is at this stage means the problem is very early in the boot process. I assume no MB LED, display, beep codes or other diagnostic help present on the MB shows an error?
Make sure the BIOS is updated to 1405. I don't think this will help, but it won't hurt either.
Boot up and run memtest86. Also run the system on a single stick of RAM for a while. Then switch to the other stick. Any difference? Bootup and run any diagnostic apps from your drive makers. Again a rule out, but worth doing.