Question Gigabyte Aorus GA-Z270X-Gaming 7 EVGA 650P2 Post-power loss intermittent refusal to turn on/post at all

[Chesschamp09]

i7 7700k;
Gigabyte Aorus GA-Z270X-Gaming 7 (rev. 1.0) / F9e bios pretty sure, but that hasnt seemed to matter;
16GB TridentZ (model # not handy, findable on request);
Graphics Unplugged/not doesnt seem to matter;
storage media connected also doesnt seem to matter connected or not;
Closed loop watercooler with dual fan radiator for CPU (model # not handy, findable on request);
EVGA 650P2 (this one is a new one sent to me from a RMA about a year ago);
Enthoo Pro M Case;
APC 650 UPS (battery has went bad, which has caused me to be reminded of this problem during the recent winter storms in the US).


The system seems to have a strange quirk related to powerloss behavior.
When losing power (either from electrical interruption, or switching off to work in the case), it will be unwilling to turn back on for indeterminate periods of time once being setup again, even though I can see that the onboard power button is lit up (and this is the only thing lit up).
Specifically, trying to turn it on, does not turn it on at all (nothing at all happens), so there's no opportunity to see status LED information when it gets like this.
I have tested it with multiple power supplies (all the current ones available still pass the basic power on test), components disconnected, the case and the onboard power button, the onboard reset button, Dual/Alt BIOS active/inactive and it appears to make no consistent difference.
Once it is able to power on successfully just once, it is completely fine again until power is interrupted again, and then this behavior returns.

This behavior has occurred as far back as I can remember, except for maybe right after I built the machine where the initial power up worked I believe.
Usually, after having it plugged in for awhile or having it unplugged for awhile will let it turn on again next time I try it, but to be honest it is more inconsistent than consistent about the exact conditions under which it will turn on again.

So I'm wondering if anyone has any potentially useful knowledge, insight, or ideas at all useful about this bizarre situation.

 

[JohnBonhamsGhost]

Gigabyte Aorus GA-Z270X-Gaming 7

a strange quirk related to powerloss behavior.
When losing power (either from electrical interruption...

if you are consistently having power outages it's likely that fuses and/or capacitors have been damaged.

APC 650 UPS (battery has went bad

you have tried using the system without this UPS and still face the same issue?

 

[Chesschamp09]

if you are consistently having power outages it's likely that fuses and/or capacitors have been damaged.

you have tried using the system without this UPS and still face the same issue?

It is usually relatively stable (and/or the UPS was still functioning as intended). I would say outages are generally the exception and not the norm.
However, during the temporal locality around the recent bout of storms, it was not stable at all, though the PC spent almost the entire time off after electrical disturbances were experienced.
I managed to get it to power on after it was over, though the day after I had it working, I foolishly decided to run some tests on the UPS (while the machine was off), which obviously involved interrupting power to the machine and haven't been able to get it to behave since.
There have been a few power issues since then as well, though of course the machine hasn't been on since the UPS tests.

If that is the case, I would guess that likely means the component I received was marginal at purchase (not that that matters now for the MB unfortunately).

I have tried, but having it plugged directly into wall outlets has no discernable effect.

 

[Chesschamp09]

Update: The core problem still exists(the odd behavior and resistance to turning on after power loss), but I have managed to get it to turn on once more. The CMOS battery was pretty much dead, and replacing it managed to eventually let the machine startup again.