Displaycable causes trouble during boot & does not let monitor sleep when computer is off/sleeping

[Lindstroem]

Hi!

I have a Samsung SJ55W and a Gigabyte 2070 Super Gaming OC. I recently bought a Deltaco Displayport 10m Cable to replace my current 2m. When i first jacked it in it worked great and was able to deliver 3440x1440 at 90hz (had to turn down from 95hz previously but thats fine). 

 

But, when the computer is off/sleeping, the monitor keeps waking up every ~5 seconds to show "Displayport" in the top left corner. Probably because the monitor is recieving some sort of signal from the GPU even though its shut off? Also, as I've read from other threads, I too have trouble booting sometimes where the monitor/monitorcable hinders the computer from correctly booting up. This can be solved by either having the monitor shut off until the computer is booted, or by shutting down the computer and shutting down the PSU and then starting the computer. 

 

I have checked the notorious 20-Pin connector with a multimeter and I did not get a signal from it. Regardless i set to tinker with the 20-Pin-connector towards the screen to render it useless. But that did not change anything.

 

I have checked powersettings and also bios settings (ErP is on for what it matters) and I have disabled wake computer via PCI to ensure that it does not deliver a steady current to graphics card.

 

As the computer is hidden away, I need to have sleep mode working so that I can wake the computer via the keyboard. Having to manually shutdown the monitor every time is quite a hazzle.

 

Anyone have any work arounds? The alternative and easiest tip to give would be "Buy a better cable". But its aggrevating that the cable itself delivers good solid bandwidth and its only this problem that makes it problematic. Also I have no stores in the vincity that sells 10m DP-cables so I need to order and take the shipping expense of returning it if other cables also shows problems. And I would prefer not to spend 100$ on a DP-cable as that could have been money spent on a better GPU instead. 

 

Thankful for any insights/tips!

[Dujith]

Is it an active cable? (you can tell by looking at the connectors, 1 should say source)

Not sure but i think most GPU's do not support DP++ and will have all kind of issues with longer cables.

 

That at least has been the case for us at the office and was solved by using active cables.

[Lindstroem]

Thanks for you response! No its a passive cheap cable, active would probably solve it but with a high added cost so would like to explore possible solutions first

 

EDIT 191024: I've gone ahead and ordered a new cable, still passive DP 1.2 but slightly more premium (40$ instead of 20$) and supporting 4k 60hz instead of 4k 30hz that was the previous cable's spec (even though it delivered 3440x1440 90hz). I've made a deal with the supplier for a free return if the problem still exist, will update on the matter 

[DonQuixote12345]

Hey OP,

Did the cable resolve your issue? I just bought a SJ55W and am having the same issue where the screen keeps waking up every few seconds when the computer is powering off. 

[lukesturr]

I also have a SJ55W and have noticed this same issue when using a displayport cable. It seems to only do it when the screen is supposed to sleep, but stops when my PC goes fully to sleep. Starting to believe this may be a defect with the monitor since y'all have the same issue. But maybe a new cable will help.