Question ASUS Maximus VIII Formula is unresponsive ?

[DukeSmilingCat]

Last evening I suddenly discovered that my file server had powered itself down, and would not turn back on.

When first applying power to the PSU, the Start and Reset button lights illuminate briefly. Sometimes the red lights on the shield come on briefly. Then nothing. No lights, no Q-code, no fans, no joy at all.

At this point I have removed the mobo from the case, disconnected and pulled EVERYTHING but the CPU (no RAM, fans, etc.), pulled the CMOS battery for an hour, and have it open-air testbenched with a brand new PSU. Still the same response.

Normally I'd be thinking dead mobo replacement at this point, BUT...

About 3 years ago this exact motherboard played possum in the exact same way. It was in my desktop at the time. Got up one morning, and same symptoms as now. Spent a pile of money to replace the unholy trinity of CPU, mobo, and RAM to get me back up and running, and then afterwards went to test and salvage parts from the "failed" system. At that point (which was several days later), the motherboard worked fine. My file server was in need of an upgrade, so I shrugged and re-deployed the mobo in that capacity, and it had been working fine until last night.

Does anyone have any insight on what to try to instigate another such "resurrection miracle"? I don't want to spend another pile of money just for this motherboard to loudly proclaim "I'm not dead yet!" a couple days from now.

 

[rgd1101]

full system spec? include brand and model of the psu

 

[DukeSmilingCat]

As it sits on the bench right now, Intel Core i7-6780, ASUS Maximus VIII Formula, and brand new Corsair RM850 PSU. Integrated graphics, no RAM or HDD at the moment.

(edit: corrected CPU spec after reseating it and actually looking at it, though it's probably not relevant to the issue. Been a long time since I've had to open this compy.)

 

[DukeSmilingCat]

Additional things now tried:

• Re-seating and re-pasting the CPU.
• Blowing off the minimal dust accumulation (it sits in an area where dust accumulates more slowly than much of the house).
• Visually inspected for damage or scorching, to the best of my ability without removing the god-awful armor cladding they put on this thing.
• Thorough olfactory test revealed no "odeur de thermal runaway".
• (edit) Replaced CMOS battery

It seems that the longer I keep it disconnected from power, the longer the lights stay on when I come back to it, and the more time that passes overall, the longer the lights stay on when attempting to power it on. Very weird, but it's up to about a full second now.