Question Computer does not power up at all, then comes back to life after a few hours

[Neriya]

I'm having a weird problem with my computer. When my computer is on, it is working perfectly well (its less than a year old). However, if my computer goes to sleep mode / hibernate or shut down during the night, when I come back in the morning and try to "wake it up" by clicking the mouse, the mouse lights will turn on but the computer will not. So after this happens I try to push the power button but nothing happens (absolutely nothing, no lights no sounds, nothing). Then I try to unplug the power cable and plug it back, press the power bottom and still - nothing happens (no lights or any sound of anything turning on) - although the lights on the mouse and keyboard are there. Afterwards I unplug the power cable again and wait at least 2-3 hours, plug it and only then the computer will Power on again. I have warranty so I gave the computer to the store I bought it from, but they cant reproduce this problem and therefore refuse to replace the PSU. They think I have some sort of power supply problem (meaning a problem with the power system in my house). I really cant think of an explanation to this phenomenon. What could possibly make my computer 'die' only after it being in a low power state(shutdown, sleep etc), and then wake up after a couple of hours? Just to be clear, if I disable sleep mode etc and let the computer run, everything works fine and nothing will happen (I let my computer stay completely on over a weak and nothing happened). Another point which might be relevant - after the computer dies and comes back to life, the computer clock is not showing the right time (the date is fine but the hour is lagging behind a few hours).

Could any of you think of an explanation to this? Which component should be the culprit?
This is my set up:
Processor: AMD RYZEN 5 2600X
PSU: Corsair CX550M 550W PSU 80+ Bronze Modular
GPU: Geforce 1660TI MOBO:
Gigabyte B450M DS3H
Thanks!

 

[rgd1101]

ssd or hdd?

 

[Neriya]

ssd

Addlink SSD 256GB S70 M.2 2280 NVMe

Though should a hard disk prevent a computer from powering on?
When I push the power bottom simply nothing happens (no light, sounds etc)
The same as pushing that button if the computer wasnt plugged (although there is a light on the keyboard).
Btw, there is a weak buzzing sound coming from the PSU when the computer is plugged (and shutdown).