At this point I can't rule the supply out completely especially if it is losing it's ability to regulate. Once the system comes up and runs for about 2 minutes and then shutoff when the expansion cards are not seen in the DM it will start right back up like nothing ever happened.
At first I thought it may be the board in particular since this was the second in the same model line when the first simply quite after a few days. When this one went in all was well for a good 3 yrs, considering what it has been put through. Of course it is also ironic that it is now showing signs of wear right when parts for the new build are being selected and ordered!
The cpu temps are far from ideal while still not too warm. After a full 16hr. run and running a full screen program even for several hours there hasn't been any indication of overheating. The new build will see one less HD there with the exact same make and model supply having just missed a good sale on the 850w version! ouch! power calculations require 587w with a 700w presently in use for the 5 satas, 5 case fans one being the 20cm top, and a larger 120mm fan on the Zalman hsf.
The Antec 900 will be replaced by the 900-2 model without the web cam dust collector tray on top! That will see another new Sata 6.0 host drive when the two storage drives and present host drive are moved into it. Hopefully this one will stay together long enough to see that going!
A contact also suspected a supply problem since he has one build running a Gigabyte board in it ruling out the particular Asus model. Once the new case is going I will be going over the entire board closely looking for any signs of a bad cap on the board.
With 3 out of 5 drives removed and sitting ilde I can then unplug each item and get in for a much closer look. It could turn out to be more then one thing. The bios shows 12.67v or slightly more when that was checked. But the initial draw during power on and post is where one concern would be if the supply is being pulled down a bit.