Question Monitor goes black for a brief second and then comes back on ?

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I am connecting the GPU to the monitor through a 20ft DP cable. It can display 4K 144Hz 10bit correctly, but the screen goes black for a second and then back on intermittently. After a few days' observations, I figured out it happens when there is a change in power, e.g. when the heater is starting/ending a working cycle (using a dedicated 240v outlet), a laptop power supply (same surge protector)/printer(the upstream surge protector) is plugged in, etc. It can sometimes happens even when I just connect my phone to the charger, but definitely it happens most often when the change in power is large. Now, I can confidently reproduce it by powering the printer on and off. In addition, when the screen goes black, no other appliances are affected, no flickering lights or anything, even the power indicator LED on the monitor is constantly green, meaning it's not a power loss, and the only thing blocked is the video signal. I confirmed this by switching to a 3ft DP cable that came with the monitor (everything else remains the same) and it solved the problem. However, I do need a DP cable that is at least 10~12ft so the cable management doesn't look like a mess. I am going to replace the cable with a 15ft one, but I doubt if that's enough, because 15ft is still pretty long. Am I supposed to also replace the surge protector, or do something else? Are there known good long DP cables out there? Are there DP cables with external power supply just like extra long USB extension cables I used for Oculus Quest?

The apartment has a very bad design of where to leave wall outlets (15A), so I have to use a heavy duty extension cord (15A 3prong) and plug a surge protector (rated 16A) into it before I can connect my PC and printer. To extend the power even further, I did a bad practice of chaining another surge protector (rated 12A), with which I power my 2 monitors, phone chargers and laptop. I have done the calculation though and there won't be overloads even when everything is running at the max power which should have left plenty of headroom. After all, I reserved 450w for the printer, but it consumes no more than 30w in idle state.

 

[Lutfij]

Welcome to the forums, newcomer!

As the saying goes with PSU's, if you have a PSU which doesn't have the necessary connectors for your devices(in your build), you either have the wrong PSU for the job or the wrong components for the right PSU. The same applies to your surge protector/power strip, if you don't have the right amount of connectors on the power strip/surge protector, then you need to get one that does consolidate your needs. Daisy chaining a power strip/surge protector is bad practice since the initial source of the power strip is rated with a certain fuse which will trip/cut when it's limit is reached, that limit won't be the same at the end of your daisy chain.

Are there DP cables with external power supply just like extra long USB extension cables I used for Oculus Quest?
If you're using them on your PC at this moment, please parse a link to them.