Intel UHD 620 Driver - Extended Display issues to Third Display in chain.

[majidmx]

We have a setup where we are using two IIyama  monitors  which have been daisy chained with a Lenovo Thinkpad with an Intel UHD 620 graphics driver.

The laptop connects to Monitor 1 (model xub2492hsn-b) via USB-C.  MST is enabled on this monitor.

Monitor is connected to a second IIyama monitor using the  Display Port.

The Iiyama xub2492hsn-b has a built in docking station.

The issue is when we extend the Display to all 3 monitors then there is no signal (picture) to monitor 2. If we try to connect from the Windows or Intel Graphics control panel we are unable to do so.

If the Display from the laptop is cloned to all three then this works without issue.

We have Dell laptops with Intel Iris XE Graphics and the setup works without issue.

Tech details of  IIyama monitor is as follows:

Signal input	HDMI x1 DisplayPort x1 USB-C x1 (Power delivery 65W)
Signal output	DisplayPort x1 (Daisy Chain MST max. 1920 x 1080)
USB HUB	x2 (v.3.0 (DC5V, 900mA))
USB-C dock	x1 (Power delivery 65W, LAN, DP out, USB 3.0)
HDCP	yes
Headphone connector	yes
RJ45 (LAN)	x1

Any help resolving the issue with extending the display to all three monitors will be appreciated.

[Jean_Intel]

Hello majidmx,

Thank you for posting on the Intel️® communities. I am sorry to hear that you are experiencing issues when using Extended Display issues to Third Display in the chain.

In order to have a better understanding of your issue, please provide me with the following:

• When did the issue start?
• What is the model of the second monitor?
• Is the issue present on always on the same display? Or does it interchange between both monitors?
• It is important to mention that Intel does not recommend using any kind of adapters and can not guarantee 3rd party products/adapters will work as expected. Use a direct connection with a single cable that has the same connection type on both ends (HDMI to HDMI, DP to DP, etc.). 
• Create a report using: 
• Intel® Graphics Command Center:
  • Open the Intel Graphics Command Center
  • Navigate to the Support tab
  • Select System Diagnostic
  • Click Generate Report
  • Select Save and name the output file.

• Intel®️ System Support Utility (Intel®️ SSU)  
  • Download the Intel SSU (https://www.intel.com/content/www/us/en/download/18377/25293/intel-system-support-utility-for-windows.html)
  • Open the application and click on "Scan" to see the system and device information. By default, Intel®️ SSU will take you to the "Summary View." 
  • Click on the menu where it says: "Summary" to change it to "Detailed View." 
  • To save your scan: click on "Next"; then "Save." 

Best regards, 

Jean O.  

Intel Customer Support Technician

[majidmx]

Hi Jean thank you for your replies. I hope you can help me sort this issue out as we have multiple users ecxperiencing the same issue using thier Lenovo Thinkpads and the monitor setuup.

To answer your queries:

• The issue has always been there, it can be temperamental in that sometimes the third monitor will come on.
• The first monitor is: Iiyama Prolite  XUB249HSN
• The second monitor is IIyama prolite XU249H3S
• It is always on the second monitor which is connected via Display Port cable to the first monitor. However occasionally the third monitor (final monitor in the chain)  has displayed and not the second
• We are not using any adapters. The IIyama Prolite XUB249HSN has a built in docking station with USB-C in, HDMI and DP inputs and one DP output. In addition it has USB ports to connect USB 2 device
• Diagnostic report attached
• SSU report attached.
• Screenshots attached.

One thing i notice today is if I disable monitor 2 then the third monitor will come on. So all three monitors are detected (laptop + 2 monitors)  but only  1 of the addaitional monitors can be enabled.

Hope you can help me sort this frustrating issue and as I say  there are no issues with a Dell Vostro with an Intel Iris XE Graphcs card on the same monitors. (screenshot attached). 

Kind regards

MajidMX

[Jean_Intel]

Hello majidmx,

I hope you are doing fine.

Were you able to check the previous post?

Let us know if you still need assistance.

Best regards, 

Jean O.  

Intel Customer Support Technician

[Jean_Intel]

Hello majidmx,

Thanks for the information provided in your response.

I understand that you are using the built-in docking station of your monitor; however, could you try connecting the monitor without using the built-in docking station, i.e using a straight connection with the monitor?

Also, I would recommend you perform a clean installation of the graphics driver. Sometimes corrupted files from previous installations of drivers can linger on a system which can cause driver updates to not work as expected. Also, it is important to mention that the Intel generic drivers are for testing, if you want, you can try installing our latest driver.

Best regards, 

Jean O.  

Intel Customer Support Technician

[majidmx]

Hi Jean so If I remove the DP connection between the monitors and use a HDMI and to connect the second monitor then yes it will work but that is defeating the object of the Daisy chain monitors which is much tidier on the desk and less fiddly for all users.

I will try a clean install and Iet you know what happens.

One strange thing I discovered today is that If I connect the Dell laptop using the Intel Iris graphics card and then disconnect and thereafter connect the lenovo laptop the three displays will work and can be extended??? Very strange behavious indeed. 

What could the Dell laptop possible be resetting?

[Jean_Intel]

Hello majidmx,

Thanks for your response.

Since you checked the unit works when using a straight connection. It seems that the issue is not related to the driver. It may be caused by the built-in docking.

Remember that Intel does not recommend using adapters (docking stations) and can not guarantee 3rd party products will work as expected. I recommend contacting the monitor manufacturer for further support about their docking station.

Best regards, 

Jean O.  

Intel Customer Support Technician

[majidmx]

Hi Jean I am not sure you know as like I say the daisy chained monitors work without any issue with Dell laptops and an Intel (R)  Iris(R) Xe Graphics card. Its something to do with sending the signal to the third monitor in extended mode.  If All three displays are cloned then all displays work. The third monitor is not getting the signal using the DP port.

[n_scott_pearson]

Let me go through the issues:

1. Intel UHD 620 supports a maximum of three connected displays. This is regardless of the number of physical output streams being utilized. Unless you have the laptop's display completely disabled, you cannot connect and use 3 external monitors simultaneously.
2. [Aside: Note that clone mode doesn't count; those 3 monitors are really only one monitor (as far as the UHD 620 engine is concerned) when they are being used in clone mode. It's thus means absolutely nothing with respect to the overarching problem.]
3. [Aside: I too find it odd that it is the second monitor in the chain that isn't being supported. It may be the the MST Hub in the second monitor orders the third monitor ahead of itself. Regardless, the issue is nothing but a curiosity as the two allowable monitors are working (presuming the laptop's internal display is still enabled).]
4. There is a problem that you haven't even seen yet. Let's suppose for a moment that the laptop's internal display is disabled and three monitors could thus be supported via the USB-C output. A separate problem is that the first monitor is also supporting that USB hub. The USB-C interface has two bidirectional communications channels. When you are also supporting USB downstream, only one of these channels is available for the DisplayPort signal and its transmission capability is thus cut in half. For example, where it could have supported a 4K monitor at 60Hz before, it can only support this monitor at 30Hz while this USB hub is in the picture. Now, in order to connect three 1080p monitors at 60Hz, you need to be able to transmit 3x3.2Gb/s or 9.6Gb/s. The bandwidth of the DisplayPort 1.2 signal supported by the UHD 620 engine is 17.28Gb/s. When this is cut in half by the need to support the USB hub, you have 8.64Gb/s - not enough to support all three of these monitors.

Ok, what to do if you want these three external monitors to work? I am suggesting:

1. You ensure that the laptop's internal display is completely disabled. Most - but sadly not all - laptops do this automatically when the laptop's lid is closed; don't just assume that this is the case; verify it!
2. Connect that first monitor using a USB-C-to-DP cable. This takes that USB Hub out of the picture (you don't need it anyway, right?).

Hope this helps,

...S

P.S. Data on DisplayPort transmission rates, etc. comes from https://en.wikipedia.org/wiki/DisplayPort.

[majidmx]

Hi Scott thanks for replying. Please see attached pictures. which is same laptop on identical monitor setups. Laptop_USBCDisplay1_DPDisplay2

You will see the setup will randomly work on one some set of daisy chained monitors and not on another. Disconnecting the main laptop display also does not resolve. I have an office full of frustrated employees.    Also sometimes if a user disconnects his laptop to attend a meeting and then comes back the second monitor will randomly stop working.

If we disable MST and clone all three displays (laptop plus 2 external displays)  this always works. However this is not what we want, we need to extend the displays. 

We could connect the first external display using the USB-C and the second via HDMI but this defeats the objective of  a less cluttered table. The USB-C charges the laptops and also connects the 2 external displays. The laptops that see the issue are Lenovo Thinkpads.

Thanks for your reply and please share any further thoughts.

Majidmx