Question PC won’t turn on but motherboard lights are on

AMKAM III

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Oct 6, 2015
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I built my PC in 2018. I’ve been using it without any problems since. I do my best to take care of my PC. I use compressed air to clean off the dust. I always shut off my PC every night.

small back history of my PC
There was a CMOS issue that I resolved by installing a new one that was more than a year ago, and sometimes there are some power outages, so I kept my PC in sleep mode for a couple of hours through my backup UPS, but then I stopped doing that. Recently my UPS battery is dead, so when the power goes off, so does my PC, but there are no issues when I restart my PC.

This morning, when I tried to turn it on, nothing would respond. The LED lights on my motherboard are lit up (indicating that it is receiving power), but the fans won’t turn on, the screen won’t respond, and the LED lights on the RAM sticks won’t glow…. Nothing responds to the power button on my case.

I did check for loose cables and the case power button cable; there were no issues there, but then while I was checking, which took around 5-10 mins with my PSU on, I pressed the power button again just for the sake of it, and my PC started. Then I shut down the computer after it booted to Windows, and I switched my PSU for 2 mins, turned it back on, the mobo LED lights on, and then pressed my power button again. No start... so I just sat there looking at my computer for another 2-5 mins with the PSU switch on, and it happened again. I pressed the power button, and my PC started.

I feel like my PSU is the culprit here. It takes time for it to charge??? or power up to its optimum level...
so rational dission is to change the psu???
like to hear your suggestions

my spec
corsair RM1000x
9900k @5.5
1080ti

thanks
 
my spec
corsair RM1000x
9900k @5.5
1080ti

When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:
include the age of the PSU apart from it's make and model.
 
CPU: 9900k
CPU cooler: Corsair Hydro Series H150i PRO RGB 360mm
Motherboard: Asus strix Z390-e
Ram: G-skill Trident-z 32gb
SSD/HDD: Crucial-P5
GPU: Zotac GTX 1080ti
PSU: Corsair RM1000x
Chassis: Coolermaster H500p mesh
OS: Windows 10
Monitor: sony tv
build this pc on 2018