Issues with monitor waking from sleep - but other monitors fine

[phrozenpenguin]

I've got an issue whereby my Benq (1440p) monitor will not correctly wake from sleep; It will wake (power up, but nothing on screen), then say no signal, and normally if I unplug and re-plug the DP everything comes back normal. Sometimes I have to unplug and re-plug a few times.

If I use a Dell (1080p) monitor then it always wakes, immediately, every time. If I have woken with the Benq, had the scenario above, the change to the Dell, it will be fine including switching resolution to 1080p not 1440p.

HD4000 using DisplayPort cable. High Sierra, 10.13.6. Rock solid stable everything else.

Any ideas - it seems monitor specific, but I don't know what to try? Menu options I have, and have tried, include:

DDC/CI: ON (vs OFF) - same result for both
Displayport: 1.2 (vs 1.1) - same result on both

Might just be the incentive I need to spring for a 4k monitor...

 

[maojinbing]

CFG_USE_AGDC no

 

[phrozenpenguin]

CFG_USE_AGDC no

Thanks - doing some reading and will aim to try this. But, can you elaborate on why it might help with one monitor but not another? Would really shortcut my reading. Thanks.

 

[phrozenpenguin]

I've been reading but don't understand enough about frame buffers to know how to tweak the one for my HD4000 to set CFG_USE_AGDC to no - or even to check what it is currently set at.

However, with testing on another machine with a different graphics card, it seemed to work every time. My next step is to put a spare GT710 into the machine and see if that fixes it. It would also gain me dual screen capability, so also a bonus and something I was planning on doing anyway.

Edit: I also found that perhaps Whatevergreen, from 1.1.5 on, might help "Added automatic CFG_USE_AGDC disabling to avoid constant issues with 4K display sleep and broken HDMI/DP ports" from the changelog.

 

[phrozenpenguin]

I've just put a GT710 into the machine and initial tests seemed to have fixed it, using HDMI connection. Further testing required and will update if it doesn't work.

All I did was untick "Inject Intel" in Clover Configurator > Graphics, shut down, installed the card then booted a couple of times. Not expecting massive graphics improvements, but if it fixes sleep that is great, and I also gain 1.5gb of system RAM back and trade a single DP for HDMI and DVI, which is useful for dual monitors.