U2715H, U3415W, daisy chain, wake issue

The monitors are not at fault here. The issue is the video card driver not re-initializing correctly coming out of sleep. This could be an operating system fault or the driver. You need to look to the video card manufacturer for a different driver. If you are already on the latest driver, you might need to test older drivers. That fact that doing a full computer reboot fixes it also means that this is an operating system or driver related fault.

I have since done some further testing. If, while the system is asleep, I turn both monitors off and back on, then wake from sleep, they both come on just fine. This clearly demonstrates that the monitors are remembering something when they go into power saving mode as a result of the system going to sleep.

Additional evidence of the monitors keeping some data actively in memory while power-saving can be found in the USB connections passing through them remaining active until they are turned off, after which they only reconnect - even get power - when the full signal returns.

As far as the machine and graphics card (AMD FirePro W5100, with latest drivers) are concerned, the two scenarios of sleep > wake or sleep > cycle-monitors > wake are identical. That there is a difference in behaviour demonstrates beyond doubt that the graphics card is sending the right signals to get both monitors working; that it is the process of waking from power-saving state of your monitors that is causing the MST signal not to be passed through correctly.

So, I ask again: how do I get this working? Please provide a firmware patch for the monitor(s) so they wake properly in this scenario.

I have not seen any reports of a firmware update for the U2715H. There is a firmware for the U3415W but it only addressed, "Fixes random screen flicker over Displayport".

"If, while the system is asleep, I turn both monitors off and back on, then wake from sleep, they both come on just fine."
Doing this forces the operating system to "re-initialize" the video card driver communication to the monitors. So you are proving that the fault is with the video card driver not re-initializing out of sleep mode.

More testing =
Test waking from sleep with the U2715H as the primary stand alone monitor without the U3415W connected to the computer

Test waking from sleep with the U3415W as the primary stand alone monitor without the U2715H connected to the computer

Test waking from sleep with the U3415W as the primary and the U2715H as the secondary connected via DP 1.2.

Per the warranty, you may initiate a monitor exchange. Test the replacement before sending any monitor back to Dell. If the replacement does not have the issue, keep it and send us the original. If the replacement has the SAME issue, the monitors were not at fault. Send the replacement back to Dell. Look to the computer operating system drivers or hardware as the culprit.

Thanks Chris. That makes a little more sense.

I will run various tests as suggested. As to the question of firmware, just because a patch doesn't yet exist does not mean that one isn't needed. (Any company that claims its product is so perfect that bugs cannot be found is the prime candidate for having the bugs.)

Once I have run those tests - or perhaps in parallel - I suggest that Dell support test waking a pairing of these monitors from sleep. A potentially relevant factor being that the failure occurs when I wake with keyboard activity, with the keyboard connected through the U2715H.

This will provide a second testing ground, so demonstrate where the fault actually lies, without having to go through the agony of getting a replacement shipped from Dell (it's not like I'm in at times they would want to deliver). If they experience similar problems, probably using a different graphics set-up, then it clearly indicates that there is a firmware issue.

Running these tests from my end will take a few days (to find the time).

I would also test with the USB keyboard and mouse plugged directly into the computer. As far as firmware updates, they are slow to come and only appear when the failure threshold is reached. That threshold is derived from the total number of exchanges for the specific issue versus total number of units sold. If they do appear, they are first installed on all used stock in our service centers. So the only way to get a flashed monitor is via used exchange.

Hi Chris,

I've finally had a chance to do the various tests. All with the keyboard and tablet plugged directly into a hub rather than the screens.

U2715H alone - fine

U3415W alone - fine

U3415W > U2715H - fine (for wake from sleep; some other issues).

U2715H > U3415W - fails as before.

So, it is definitely a problem with the U2715H.

Which may additionally be explained by two further aspects:

* There is a USB 'device' in each of the monitors that identifies as "Texas Instruments USBtoI2C Solution". At least, it does in the U3425W. In the U2715H, it is an "Unknown USB Device (Set Address Failed)".

* The read USB port on the U2715H is misaligned with the shell, so nothing can be plugged in to it.

It's likely that the USB device failure - possibly something attached out of alignment - is the underlying cause.

So, does the exchange option allow me to choose the day? Or will it turn up randomly, when I am off on a client's site?

The exchange just shows up. There is not a way to choose the day it arrives.

And returning to that question of actually getting the exchange process started… HOW? The Dell support site is arranged to avoid giving any way of actually contacting Dell. Is it only by phone? Or is there an online way of doing this? (Country-specific: UK)

The variables are explained here.

Per the sticky, Dell will provide a 3 year warranty starting on the original purchase date as shown by the service tag number. If the monitors do not have a service tag number,  Dell will provide a 3 year warranty based on the monitors 20 digit PPID serial numbers date code start date. We are up to revision A02.