Power supply or motherboard issue

Apr 2, 2018
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Hi, here are specs to start with,

i7 8700k
Gigabyte Z370 Aorus gaming 5
4 x 8gb 3200mhz g skill
Gtx 1080
2x M2 drives
2x 3.5 hdds
1x 2.5 ssd
Corsair HX1050 5+ years old


This psu of this system is powered through a 750va ups with surge protection, there were some mains power fluctuations a couple of days ago that would trip the ups, and some other pulse like events were the power wasn't cutting completely. Have had trouble booting since, initially pulling the cmos battery out and a power flush would work, but had to pull everything apart yesterday as the system would crash just after the motherboard logo would come up, rebuilt without graphics card, and would boot to OS ok, then added the graphics card and no boot. Up until now I had been using the pcie power connectors out of the main bundle of cables from the psu with the 24pin etc which was fine. Seeing as it wouldn't boot with the graphics card, I tried some of the modular outputs on the psu (and cleared cmos) and it booted fine. Since then it was shut down and booted fine while still connected to mains power, but have since moved it and had to clear the cmos again to boot.

I think maybe the psu or motherboard is the issue though everything is fine under load once booted, is it possible for separate lines out of the psu to fail such that I wouldn't? would it be worth replacing the cmos battery? given that I had a successful boot -shutdown-boot after switching to the modular outputs on the psu but since relocating and disconnecting from mains have had to clear cmos.
The debug codes on the motherboard seem normal in all cases and it seems like the boot is failing after bios, the post beep sounds normal as well, not sure if it would change though given the presence of the dr debug.

Any advice welcome, thanks.
 
Apr 2, 2018
2
0
10


It's been on F4 since I built it around Christmas. Have moved the system again and had no problem booting.If or when the problem arises again I'll try F5. Thanks for the input.