Question My pc harmed my monitor?

Dec 8, 2022
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I just bought a new Psu and a new case because my last psu broke. So me and my friend built the pc and when I connected my pc to the monitor everything looked fine until the screen started having issues those coloured lines all over the monitor. I unplugged the monitor and plug it again it works for a minute as usual and then the coloured lines begins.
Is the monitor completely broken and I need to buy a new one?
and what caused the monitor to do this? And how do I fix it?
 
Dec 8, 2022
3
0
10
The screen even when not connected to anything it is working for a minute and then the coloured lines begin.
So if that’s the case the only thing I can do is to replace the gpu?