Question Flickering Black Horizontal Lines on my Monitor

[porgieb]

Hello all,
About an hour ago, I noticed that Black horizontal lines, about 1 pixel high and stretching from end to end of my monitor horizontally, had started flickering on my screen. Sometimes it is just 1 line at the top, but most times it happens, the lines go from top to bottom of my monitor, I would guess about 100 lines. It happens every 5-10 seconds or so, and nothing I have tried seems to fix it.
I have tried swapping HDMI cables and updating GPU drivers, to no avail. I dont have a spare monitor to try swapping to. I have powered off both the monitor and Pc and still nothing.
I have a GTX 970, and BENQ BL2420PT Monitor.
I plan on opening up my PC and giving it a clean tomorrow, but until then any help or ideas would be appreciated.
Thanks

 

[RaidersUnited_]

As weird as it may sound, Have you tried updating windows? One of my monitors randomly started flicking this morning I tried everything as the same as you did then I thought there might be a windows update so when I checked there was but it had failed, So I retried the update and it starting downloading then install the update and that managed to fix my flickering issue.

 

[porgieb]

So I tried this and the issue persists. However I have tried connecting my monitor to my PS3 and I still get the lines so it is a confirmed monitor issue.