Missing refresh rate options on display connected to Thunderbolt hub to Iris XE graphics

[GabrielTVG]

Hi! I have this setup:
-Nitro 5 AN517-55 Laptop with Intel 12700H and Iris XE Graphics and HP Elitebook G10 with Intel 1345U processor and Iris XE Graphics, both running Windows11 Pro 23H2 
-Dell WD22TB4 Thunderbolt 4 Hub
-Dell Alienware AW2723DF 240HZ ( and up to 280 HZ support ) monitor connected through DP-Type C cable to the Hub

The hub does support the 280HZ of the display and the option does show in windows when selecting the refresh rate option.
The problem is that when i unplug the hub and connect it back again, i get the options limited to 144HZ until I restart any of the laptop I do this to, then the 280HZ option comes back. If i try to use the display with HDMI or DP, i get only up to 240HZ however the option always remain, not mattering how many times I plug/unplug the hub while any laptop is on.

Any ideas how can this be fixed or can be done about it? The hub is up to date with the drivers. I don't use the DP-DP or HDMI cables because I lose the 10 bit color and is 8 bit with dithering + the 40 HZ ( not that much of a problem that ) . If I need to post anything else or is posted in the wrong area, sorry about that, just let me know what needs to be done and will try to fix it.

[Mike_Intel]

Hello GabrielTVG,

I hope this message finds you well. 

Were you able to check the previous post?

Please let us know if you still need assistance.

Best regards,

Michael L.

Intel Customer Support Technician

[GabrielTVG]

Hi! No updates for now, I did not yet manage to get in touch with Dell Support as their support page is very convoluted and on their forum I did not yet get an aswer. I will try this week again to see if I can manage to write them related to the issue.

[Mike_Intel]

Hello GabrielTVG,

I hope you are having a good day.

Since you are now contacting Dell for further assistance, I need to close this inquiry. 

If you need further assistance, please post a new question as this thread will no longer be monitored. 

Thank you and have a great day. 

Best regards,

Michael L.

Intel Customer Support Technician

[MUC]

While I still can't offer a solution to the original problem, this is also interesting:

Dell WD22TB4 Dock review and Teardown

The fact that only 2560 x 1440 @ 240 Hz 8-bit with Dithering is available when hooking up the monitor via the DisplayPort connector also indicates that DSC is not being used or that the Intel JHL8440 Thunderbolt 4 controller does not recognize the need for DSC when hot plugged. The above signal is the maximum within the HBR3 protocol on DisplayPort that can work without DSC.

The Synaptics VMM5331 chip can usually be diagnosed with a tool. Version 9.1.7.0 of this tool is attached. If you connect the monitor via DisplayPort you can use the tool to see what is going on.

• Right-click on VmmDPTool64.exe
• Select Run as administrator
• If the tool says it can't find a Synaptics MST DP Hub IC, then unfortunately we are done.
  If not, you can do this:
  • Select the Debug tab
  • Click on "I/O Timing info"
  • Diagnostic data in the status window should then look something like this (an example from my hardware environment):

[GabrielTVG]

This is what it shows. Interesting that it show DSC is enabled as right now from the monitor at least it is disabled, maybe it is enabled from the DP port of the hub? Also it shows the same thing before and after restart of windows.

 

[GabrielTVG]

Laptop power plan is put to the Ultimate performance mode, all things related to drivers are up to date ( hub, integrated/dedicated GPU, display, BIOS etc. ). As stated in the original post or in the first replies somewhere, the options are not available until full windows reboot, that is why this post was made originally. Other Thunderbolt ports are not available but since this problem is on 2 different powered Intel Iris Xe GPU powered windows , with 12th and 13th gen CPU's with Thunderbolt 4, it is most likely a display/hub/software/driver issue somewhere. I tried to get in contact with Dell Support initially through the Dell Forum as I did here, but the post barely got like 15 views and no replies and the actual assistance process is abysmal and I have to contact them while in the working hours which I did not manage yet.

[GabrielTVG]

For the others users that posted here but for some reason I cannot see the replies in the forum but I have them on the mail, quick summary of what was recommended and what was done/already done and said:
- manually reselect 280 HZ: as stated in the original problem, the option is not available until full restart of windows, not even video driver reboot or explorer restart does not help
- update Thunderbolt drivers: updated all drivers I could: monitor, Iris Xe Graphics, Nvidia Graphics, BIOS, Hub, anything I could think of. The Thunderbolt driver from what i managed to research and see, on W11 it is more or less bugged, and whatever I do, this is what i see in ThunderBolt Control Center

- check power plans/power savings: laptop on Ultimate Performance plan, Hub does not go in power saving, only if nothing is connected to it
- use DP-DP/ HDMI-HDMI cable: as stated in one of the replies, using any of the ports like HDMI or DP goes through a chip that limits options, highest option available is 240HZ 8 bit or 8 bit with dithering.
- test another cable: no way to get another Type C- DP cable with high bandwidth to manage to test that option. Also if the option is there in the first place, I don't think the cable is the problem honestly
- connect hub with laptop off/ power cycle it: isn't the option of hot plugging the convenience of actually not restarting everything and reopening everything every single time i want to use it between 2 laptops...?
- check monitor settings: already checked, 280 HZ is there, can be used anytime continuously
- test without hub: already done, the option is always there any time I (un)plug, but I need the hub as i literally have 2 monitors, keyboard, mouse, headset and other stuff connected that i have to change between 2 laptops

[GabrielTVG]

Another update of things I thought of and tried, @MUC you might find this interesting or get more ideas from this: I tried to use the monitor without DSC, as the bandwidth calculated for the setup should allow to use all 1440P 280HZ 10 bit color and still be in the 40 Gb/s limit of Thunderbolt 4. And it does work.
However
Trying to hot plug the hub, as in the original post, I get the same problem, but even "worse": option limited to 120 HZ now and Use HDR options bugs out and stays to Off and can't turn it back on until full windows restart. I will try soon the tool you mentioned in the replies above and will write the response there after I tried it and see what happened.

[MUC]

Interesting diagnostic result.

It shows that DSC is enabled within the dock between the Intel JHL8440 Thunderbolt 4 controller and the Synaptics VMM5331 DisplayPort 1.4 Multi-Stream Hub Controller, but not when outputting to the DisplayPort connector.

VMM5331:

Rx = Receiver (from JHL8440).

It receives a MST (Multi Stream Transport) DSC stream and then:

Tx = Transmitter:

This decompressed output represents 98% bandwidth usage of DisplayPort 1.4 HBR3.

Refresh rate, bit depth and pixel clock could only be increased (on the monitor) by passing a DSC stream through and not decompressing in the dock. Decompression should then be done by the monitor.

This would need to be investigated further with a Dell developer.

[GabrielTVG]

I hope it was clear that DSC from the monitor right now, when that screenshot was also made is disabled and maybe that is why it uses so much of the bandwidth.
Also I guess there is nothing else we can do beside trying to somehow get in contact with Dell Support?

[MUC]

Yes, I read the test conditions above. And yes, we would need a Dell expert to help us now.