S2716DG, A07, DP will not wake with two inputs

Question

I have an issue after following some of the advice on these forums with my dell monitor not waking on an input change from HDMI to DisplayPort. I have factory reset the monitor and disabled monitor deep sleep to no avail.

For my setup I have two computers and two monitors (one being the Dell). Computer 1 is connected to both the Dell S2716DG and my secondary monitor via HDMI. Computer 2 is connected to the Dell via DisplayPort and the secondary via DVI. There is a USB KVM switch between the two computers for my mouse and keyboard.

Switching from DisplayPort to HDMI will always work with the Dell. However, switching back from HDMI to DisplayPort will not work. The screen simply flashes the HDMI screen for one second and then goes to the DisplayPort black screen and eventually power saving mode. I've noticed that this only happens after being on the HDMI input for a long period of time. The secondary monitor (HDMI to DVI) has no problem when doing this.

The only solution I have found is to physically disconnect and reconnect the DisplayPort cable from the computer to reset the handshake. Any help would be greatly appreciated!

* What is the 20 digit alpha-numeric monitor serial number and A0x revision? CN-0JCVN0-QDC00-7BD-14CU A07
* To what computer model is the monitor attached? Windows 10 PC
* What video card/GPU is in the computer? NVIDIA 1070
* What video out ports are on the video card/GPU or computer? DisplayPort, DVI, HDMI
* List all monitor cabling attached to the computer and the ports they are using: DisplayPort from PC to Dell monitor. DVI from PC to second monitor.
* What Windows power plan? High performance. PCI link state off.
* Resolution: 2560x1440, 144Hz, G-SYNC
* Was the monitor purchased directly from Dell or some reseller? BestBuy

DELL-Chris M · Answer

I would remove the secondary monitor and all of its cabling from the troubleshooting. So two computers to one S2716DG. Built on November 13, 2017. Test this. Disable Nvidia G-SYNC in the Nvidia Control Panel. Enable ULMB in the monitor Menu and use the S2716DG at 120Hz. Now try switching from HDMI to DP. For my notes, send me via Private Message the service tag number.

kingdeslok · Answer

So I disconnected the secondary monitor and set the Dell to 120Hz with ULMB. I don't think it's been long enough for the bug to happen (where I'm working on my secondary computer for awhile and try switching the one connected via DisplayPort) but I did find a way to replicate 100% of the time.

It seems if I put the computer connected to DisplayPort to sleep, switch to the computer connected through HDMI, wake up the DisplayPort computer, and then switch back the input to DisplayPort I run into the issue every time. I'm guessing it has to do with the act of waking the computer up from sleep sending a signal to the DP connection to initialize. Maybe this would happen with any monitor that uses DisplayPort?

I'm curious if something similar is somehow happening to my computer after idling for awhile (the power settings are set to never put the computer to sleep/hibernate).

DELL-Chris M · Answer

More data needed = Computer 1 = Dell ???, GTX 1070, Windows 10, Connected to S2716DG HDMI in via HDMI to HDMI cable Computer 2 = Model, GPU, OS, Connected to S2716DG DP in via what cable?

kingdeslok · Answer

Sorry, whenever I'm referring to the Dell I mean the S2716DG. The other monitor is a BenQ.

Computer 1 = Dell S2716DG, GTX 1070, Windows 10, connected to S2716DG via DisplayPort cable.

Computer 2 = DellS2716DG, Macbook Pro, Intel Iris Pro, macOS High Sierra, connected to S2716DG via HDMI cable.

DELL-Chris M · Answer

I need the second computer connected to the S2716DG via HDMI to HDMI cable to be a Windows PC. Then retest the S2716DG switching from HDMI to DP. The Displays Team will not test using the non-validated Apple proprietary operating system and hardware.

DELL-Chris M · Answer

Perhaps I can use the one Windows computer connected to the S2716DG via the 1070's DP and HDMI port and test that behavior?Hmm, I have never tested in that way. I have no idea how Windows 10 would react to that test.

kingdeslok · Answer

Hmm it's going to be a little tough for me to get my hands on another Windows machine, but I'll see what I can do and report back. Perhaps I can use the one Windows computer connected to the S2716DG via the 1070's DP and HDMI port and test that behavior? Regardless I'll likely have to switch back to the Mac/PC setup for work purposes.

So if Apple hardware is out of scope for the support team then I'll just chalk up the partial solution to simply ensuring the input is selected as DisplayPort before waking the computer.

kingdeslok · Answer

Alright, so I got around to testing this. Basically I hooked up the S2716DG to the same computer using both the HDMI and DP outputs of the 1070 GTX and I got the same exact result as though I was using the MacBook.

I wake the computer from sleep while the S2716DG is selected on HDMI input and then switch over to DP input. The screen briefly flashes and then goes into power saving mode. It seems to work fine when doing it the other way around.

So it seems to me that the DP input has to be selected when you wake a computer from sleep or else you're out of luck until you resleep the computer or manually reconnect the DP cable.

Monitors

S2716DG, A07, DP will not wake with two inputs

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