Question Monitor flickering after installing new psu

[Manishh]

This problem used to happen 2 years ago too but rarely like 2 times in a week and mostly after 7pm (idk why). At that time I thought it was because of my 180watt psu, Then around 1 month ago I bought a old used 750ti and surprisingly it was working great and my monitor was not having this problem.
I knew that 180watt was not enough and keep using it at its max might blow up my pc. I went to a PC Shop and by mistake bought a 250watt psu, I knew it was not enough but I could only return it after 2 days and So, I tried it on my pc and I was having the monitor flickering problem, I thought it was because of the <Mod Edit> local brand of the psu (iball). I changed it to my Chinese 180watt psu(which was plugged before) and my monitor was not showing flickering. After 2 days I changed it and got a 'Ant Esport 400watt psu'
https://www.amazon.in/Ant-Esports-VS400L-Power-Supply/dp/B09XQRMBCK/ref=sr_1_3?crid=3DSN298BH6BVF&keywords=ant+esports+psu&qid=1671118223&sprefix=ant+esports+psu,aps,220&sr=8-3&th=1

And after installing, My monitor started having the flickering issue even though its a good company PSU(i think). I disassemble and assemble PSU and GPU 2 times and It didnt work

TLR! = Monitor started flickering after installing new PSU(I do say read full story).

Things to clear:
1: GPU have no fault here, I tried it on my friend pc and it was working like charm
2: My monitor don't have this problem either, When I only start monitor and not pc to see the 'No cable plug' screen. There is no flickering on it and not when I open monitor in built setting.