How old and what psu
its like 2 years, im not sure what PSU it is, can i check it without cracking open my case? whole pc is fresh since 2 years.
Id also like to add i had a second monitor plugged in for the most part aswell. HDMI to tv.
I doubt they'd cause that unless you were really close to maxing it anyway.
Reason I'm saying unplug the GPU is cos if your monitor is still plugged into the GPU it's still sending information through it to the HDMI or VGA port or whatever. Get rid of it completely run with onboard graphics and use your motherboard ports to completely bypass the GPU. If you're not getting artifacts without the GPU then it's something on the GPU that's the issue.
My monitor isnt connected via my GPU afaik, its connected just below that jack. That could just be another gpu input though. I'll have to try to switch it.