The Problem

I have a reasonably decent video card, a XFX R9 280x TDBD.

I recently bought a second monitor and hooked it up. Old monitor was running on HDMI, whilst the new monitor was running on a Mini DP to DP connection.

I fired it up and my new 23.8 Inch AOC IPS display started flickering and jumping around??? It was a full hoizontal artifact across the screen that seemed to jump around and jitter and jutter when I moved the mouse or opened applications.

Investigation

To me it appeared to be a video driver software issue. I tried playing around with the display settings and by choosing different preferences I actually made the Jitter/Jutter move from appearing on my new display to my old display, WTF? It must be a software issue if I am able to impact which screen the problem appeared on by changing software settings.

I tried full clean driver installs. I upgraded to the latest driver, and then when that didn’t work I downgraded to 17.11.1. No change.
I tried running from different ports, HDMI, DVI and DP and still no luck so not the cables.

I eventually found that in the Radeon Settings, I could open preferences and click “Restore Factory Defaults” and it would stop the problem.. However on the next reboot it would be back.

The solution

I finally googled a discussion on toms hardware where it was suggested that:

Check the clocks of your video card. They are not supposed to downclock as much with two monitors. The memory and GPU core clocks should be higher than the normal idle, otherwise they can’t handle 2 monitors correctly

That makes sense, running two monitors requires a little more oommpphhh, and if your video card is running under-clocked then it may struggle.

I downloaded and installed the GPU-Z and went to the sensors tab and noticed my core clock and memory speeds seemed to be way down.
I watched when I clicked, “Restore Factory Defaults” and sure enough the Clock and memory bumped up by almost double, and the flicker stopped.

So I then remembered that I had installed MSI Afterburner at some point in the past.
I fired it up and checked how that was configured. It seemed that an empty profile (i.e. the memory and core clocks set to minimum) had been loaded and set to “Apply overclocking at system startup”.

So the problem was caused by a down clocked video card, not being able to handle running two monitors.

Problem solved, and it has not flicker once whilst I wrote this post 😛