Screen flickering on dual monitor

[xyboox]

Hi,

please have a look at this video:

Can you please give me a hint on where to look for troubleshooting?

My hardware config is:
MB: Asus Z87-A
CPU: i7 Haswell
Video: NVidia GTX 650Ti
Displays: Lenovo Q27Q-10 on HDMI ( primary ) + Benq BenQG2222HDL on DVI

Thank you!

 

[kylec]

Can you please give me a hint on where to look for troubleshooting?

I can't quite tell whether the Benq display is also having issues, or just reacting in some way to what's going on with the other one.

Does your 650Ti have a third port?

 

[xyboox]

@kylec the video card has 1 x d-sub, 2 x dvi and 1 x hdmi. You think of something along these ports?

In fact, the flickering happened also back in the days when I only used one display ( the Benq one ). It just continued after connecting the second one also. The frequency is from... once in a couple of days to... twice a day. I couldn't spot a pattern on when is happening.

 

[kylec]

Do you overclock? With stuff like this, it's always good to verify that the problem occurs also using stock clock speeds (memory too).

 

[xyboox]

Do you overclock?

No, running on standard speed.

 

[kylec]

I'm not sure. I'd probably try moving the HDMI monitor to the 2nd DVI port with an adapter. It doesn't sound like it's related to the type of port, though.

Did you enable HPET? (And set to 64-bit, although I think maybe Z87 is new enough it doesn't have the option?)

 

[xyboox]

No HPET in my bios. Since the issue manifested itself also back when I was using just the dvi with Benq display, does it make any difference if I connect the 2nd display on dvi instead of hdmi?

 

[kylec]

Probably not, but I'm running out of ideas!

@Feartech, what do you think?

 

[xyboox]

Anyone got these symptoms yet?

 

[Edhawk]

Can you clarify the following:

• You have tried a different HDMI cable when connecting the Lenovo display? Do you see the same flickering issues?
• The flickering only happens with macOS, i.e. if you use the same dGPU and cable with either a Linux distro or Windows you do not see the same flickering?
• Which version of macOS are you running?
• Have you tried running the system without WhateverGreen.kext (WEG)? I ask this as one of my systems with an Nvidia Quadro K4200 dGPU behaves poorly when using WEG. Works perfectly without WEG.
• Do you have your Intel iGPU, assumed HD 4600, set to run 'Headless' or can you see details for the IGPU in the System Information > Graphics/Display report?
• With the IGPU fully enabled, does the flickering occur when you connect the two screens to your motherboard HDMI and DVI ports?