Question Desktop Computer Powers Up only after 15-20 minutes after switching on the UPS

[VBTTS]

Desktop Computer Powers Up only after 15-20 minutes after switching on the UPS
My system config :-
Corsair cx450
Amd ryzen 5 3400g
Asrock b450 pro 4
256gb Mx500
500gb bx500
2tb wd blue
4tb wd blue
Corsair carbide beloved patriot delta

It worked without any problem since January 2020.
A month back apc bx600i stopped working so I changed my livfast 850va inverter to ups mode and connected the computer to power outlet directly.
7 days Back it stopped working. I tried the wire test and noticed that the psu is not working so next day I got it checked in the local market as the 5 year warranty of the psu is over.
Psu got repaired for 800 and it worked fine that day.

next day the situation was the same - it was not working again.
I took it to the same local shop where it got switched on immediately. He switched it off and on and it worked.
He said that it must be the power cable.
I took it back. Used a new cable but then again it was dead.
Tried it with a new apc bx600i ups, then directly with power outlet but nothing happening.
Monitor was on with the same points.

I tried 2 power cables, on ups and directly on the power outlet but it was dead - no light on the power switch, no fans worked.
Tried an ancient smps with the same power cable and it worked with wire test. Unfortunately it can't be used to test the system as it is ancient and doesn't have necessary connectors.

after few hours, i connected the psu back, just the 24pin and mb connector and it got switched on, showed bios. i connected everything else and it loaded windows. it worked fine then.

next morning i switched it on and it worked for some 4-5 hours. i went out at around 3pm and came back at around 8.35pm. it didn't start then. i left it and tried it around 9.22. it started again and worked fine.

yesterday morning again it was dead, no power on, no fans start working. after 15-20 minutes, i tried and it started and worked for the whole day without issue.

today morning it was the same scene. it worked after 15-20 minutes.

i noticed one thing - when it starts after this dead episode, it shows an incorrect time. cmos battery is new, installed just a month back. is this something related to motherboard?

which ghost is this?
Thanks.

 

[Aeacus]

which ghost is this?

Short answer: penny-pinching.

Long answer: cheaping out on PSU and UPS.

There are 3 variants of Corsair CX PSU, with different labels on it's side. Which one you have:
1. Black label with green lettering.
2. White label with black lettering.
3. Black label with white lettering.

Psu got repaired for 800

By whom? Certified Corsair repair center? Or some random bloke down the street?

I took it to the same local shop where it got switched on immediately. He switched it off and on and it worked.

Well, if your car won't start and you take it to the mechanic to fix it's engine, which mechanic does, so that engine starts, but mechanic doesn't make car drivable, then car isn't repaired. Just because you can turn the car engine on, doesn't mean car is able to drive.

And same has happened with your PSU. Just because it was repaired into a state where it can turn on, doesn't mean it is repaired into a state where it is able to output any load, other than the idle.

is this something related to motherboard?

It is power delivery. PSU. And UPS too, if you have connected PC to it.

When it comes to power delivery, you can not cheap out on it's components. Meaning PSU and UPS.
Since PSU powers everything, it is the most important component inside the PC.
Hence why NEVER cheap out on PSU! Also, never buy used PSU either.

Also, cheaper UPSes, either output square wave or simulated sine wave. Your APC UPS outputs simulated sine wave and that isn't compatible with Active PFC PSUs, like your Corsair PSU. Only true/pure sine wave is compatible. So, do get proper UPS as well.

New PSU is a must.
There is no such thing as good and cheap PSU. If you want good and cheap PSU, you have to buy two PSUs: the good one and the cheap one.
You already bought cheap PSU. Is the next PSU you buy also cheap one? Or are you going with good PSU this time around?

If good one, then Tier A is proper. Like: Seasonic Focus/Vertex/PRIME, Corsair RMx/RMi/HXi/AXi, Super Flower Leadex Gold/Platinum/Titanium.
PSU tier list: https://docs.google.com/spreadsheet...JWkc/edit?pli=1&gid=1973454078#gid=1973454078

Tier A- will do too, while Tier A+ is preferred.
550W does fine. 650W doesn't hurt either.
(My 3x PCs are solely powered by Tier A PSUs. Namely, i have Seasonic PRIME 650 Titanium (Tier A+), Seasonic PRIME Ultra 650 Titanium (Tier A+) and Seasonic Focus PX-550 (Tier A). Full specs with pics in my sig.)