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Screens blink on/off when I daisy chain my 3 new U2415!

Just bought 3 new U2415's for their daisy chaining capability.  When I connect them as per directions, they do indeed daisy chain, but almost immediately they begin blinking to black screen and on again, like lights on a Christmas tree (only slower). 

My setup:
Mobo:  Asus P8P67
GPU:  Radeon HD 6850
SSD:  Samsung 850

At first, all I could get the monitors to do was mirror each other. 3 expensive monitors showing the same thing doesn't work for me.  After 3 hours with Dell phone support they finally told me no mas without solving the issue, because the monitors were not connected to a Dell PC.  Disappointing.

So, I disconnected all my drives except the SSD and did a fresh Windows 7 install from DVD, and then downloaded and installed all of the Windows updates. Installed Dell monitor driver off of DVD that came with monitors. Updated Bios and latest chipset, GPU drivers and AMD Catalyst Control.  Nothing else is on the SSD besides Win 7, Windows Security Essentials, Malwarebytes. No other storage drives.

I reset all of the monitors to factory settings and then Enabled DP1.2 on the monitors #1 & #2.  Monitor #3 was already Disabled.  Voila...Windows recognized 3 independent monitors and I was very happy. Until they started to blink on and off after a few minutes.  The AMD Radeon HD 6850 specs claim to support:

  • DisplayPort 1.2
  • Max resolution: 2560x1600 per display
  • Multi-Stream Transport
  • 21.6 Gbps bandwidth
  • High bit-rate audio

My monitor cables are DP1.2 and brand new. Windows is fresh, bios and drivers are up to date. This is driving me crazy.

So, anyone have some ideas on what I am doing wrong? Is there a super secret Dell pay support line that I can call? I am willing to pay, provided I get this solved.

Thanks!

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

I would start by turning everything off. Disconnect monitors 2 and 3 from the setup.

* Test monitor 1 by itself. Does it have the blinking issue? (Y/N)
* Turn the computer and monitor 1 off

* Add monitor 2 in a daisy chain:
Does monitor 1 have the blinking issue? (Y/N)
Does monitor 2 have the blinking issue? (Y/N)
* Turn the computer and monitor 1/2 off

* Add monitor 3 to the daisy chain:
Does monitor 1 have the blinking issue? (Y/N)
Does monitor 2 have the blinking issue? (Y/N)
Does monitor 3 have the blinking issue? (Y/N)

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

Hi Chris...thanks for your reply.

#1 by itself direct connect via DP1.2 cable to GPU...no blinking

#1 daisy to #2....both begin to blink after a minute or two

#1 daisy to #2 daisy to #3.....all three begin to blink after a minute or two.

Any thoughts?  Is my GPU capable?

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

Can you test monitors 2 and 3 as  #1 in the chain? Is there another desktop computer to test them on?

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

Chris...I have tested every combination..with same result.

Thinking this might be caused by an older GPU, yesterday I decided to upgrade the majority of my system and purchased and installed:

CPU:  Intel Core i7 4790K

MoBo:  Asus Z97-A

OS:  Win 7 Pro

My 3 U2415s are all REV A02

I did retain Corsair HX650w PSU, which has more than enough power to drive my rig and Cooler Blaster 212+ to keep the i7 chill.

So...I essentially have a brand new and up to date system.

What is going on here?

The good news is that the random black screen blinking has decreased from once every 90 seconds/per screen to about once every hour or so.  

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

I hit "Post" to fast.

I meant to say that even after doing all of these upgrades to create a very current system, the screens all still randomly go to black and then back on, when in daisy chain.   No issues if running only a single monitor.

The good news is that the rate at which they black screen blink has decreased.   I did notice that when I was in the midst of copying 12 gig of files from one of my HDDs to my SSD the pace of blinking increased significantly, similar to what I saw before upgrading components.  How could this be impacting MST?

What is going on here?

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

I also forgot to mention that I purchased a new GPU as well:   Sapphire Radeon R7 380

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

Did you install the latest AMD driver for the Sapphire Radeon R7 380? If yes, the only other thing to try is to get three monitor exchanges there. Then, test all three replacements. You will have six there to mix and test. But by the end of testing, three will have to be sent back to Dell.

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

Hi Chris....I wanted to give you and the community an update.

I upgraded my GPU, again:

From:  Sapphire Radeon Nitro R7 360 2GB (new a week ago)

To:      Sapphire Radeon Nitro R9 380 4GB (yesterday)

Since I did the swap yesterday morning, I have only seen one monitor flash to black screen, once.  The new card is faster and has twice the memory capacity.  I don't know which of those features caused the change in behavior, but I am just glad the monitors aren't blinking, for now.  Based solely on my experience, it would appear that in order to daisy chain the U2514s, you need a reasonable recent  and powerful GPU card.  If this is the case, where does Dell disclose this is minimum system requirements?  Is there a Knowledge Base discussion on this issue?

QUESTION:  Can the included Dell DP to Mini DP cables be used to daisy chain?  After I saw some stability in the monitors I tried to use these cables to daisy chain #1 to #2 and #2 to #3, as I wanted to return the $27, 3ft Full DP to Full DP cables I bought at Micro Center.  Once I booted up, only #1 lit up and went to Window.  #2 and #3 flashed "No DP Cable".  I swapped both mini to full DP cables to see if one was bad, same result.  Why won't these work?

Thanks for your help.

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RE: Screens blink on/off when I daisy chain my 3 new U2415!

If this is the case, where does Dell disclose this is minimum system requirements?
* We only listed this in the Manual =
U2415 supports the DP MST feature. To make use of this feature, your PC Graphics Card must be certified to DP1.2 with MST option. The default out of factory setting in the U2415 is DP1.1a. To enable MST connection, please use only DP cable as provided in box (or other DP1.2 certified cable) and change the DP setting to DP1.2.

Is there a Knowledge Base discussion on this issue?
* No. I cannot find one.

Can the included Dell DP to Mini DP cables be used to daisy chain?
* They should:
Sapphire Radeon Nitro R9 380 4GB DP out --> U2415 DP to mDP cable --> #1 U2415 mDP in (DP1.2 MST Enabled)
#1 U2415 DP out --> U2415 DP to mDP cable --> #2 U2415 mDP in (DP1.2 MST Enabled)
#2 U2415 DP out --> U2415 DP to mDP cable --> #3 U2415 mDP in (DP1.1a Enabled = DP1.2 MST Disabled)

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