Re: DisplayPort/USB-C connection to 4k monitor supporting only 30Hz refresh rate (2024)

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ThinkPad Universal USB-C Dock

Lenovo ThinkPad P15s Gen 1

Dell UltraSharp 27/32 4K - USB-C Hub Monitor – U3223QE

Please connect the USB-C cable that came with the monitor to port (5) on the monitor. Plug the other end into one of the USB-C ports on the left side of the laptop. Please thencreate aReport for Intel Graphics Driversandattach the output file here.

Please find the report attached.

I have indeed used a USB-C -> USB-C cable included with my monitor, port 5 -> thunderbolt on the lenovo

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This is an unusual problem. Over the cable, the monitor reports that it can handle 4K @ 60 Hz with the video timing as per standard. When I simulate this situation on my NUC11 device, then it works. I do have Iris Xe graphics and Windows 11 though.

Your driver version is also the one provided by Lenovo on the website, judging by the version number. Did you install the driver yourself? You can try installing the Lenovo driver through it again.

I think the monitor and connection are fine, so you can either ask Lenovo what's going wrong here or we can try to force the 60 Hz into the driver using a third-party tool. I can't guarantee it will work though. It's a bit of trial and error, but it's harmless. Please let me know how you plan to do it.

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Please let me know more about this 3rd party tool while I am waiting to heard by Lenovo.

Reinstalling the driver didn't help. (Best drivers are already installed)
Thanks for assisting me!

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• DownloadCustom Resolution Utility (CRU)
• RunCRU.exe
• Make sure theactiveEDID is that of the DellU3223QE.If necessary, select from the drop down menu at the top.
• In the first step, please do not change anything, just take a screenshot and post it.

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4K@30Hzis all you are going to be able to do here.You have a 10th gen processor that is only capable of 4K@60Hzif the entire USB-C connection is dedicated to DisplayPort graphics. If the connection is also supporting USB communication, then only halfof the possible bandwidth (two of the four differential pairs) is available for DisplayPort communication. This means that 4K@30Hzis the best you will do.

...S

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As I understand, the monitor is now only connected via the included USB-C cable and the manual of the laptop says 4K @ 60 Hz. But of course it is true that 4K @ 60 Hz only works if the DisplayPort HBR2 protocol is sent on 4 lanes.

In your screenshot you can see the Extended Display Identification Data (EDID) that the driver read from the monitor. 4K @ 60 Hz capability is available. However, it is not available for selection for you in Windows. Instead, 4K @ ~30Hz is available for selection, but this does not appear in the screenshot. That's strange. If 4K @ 30 Hz is not present in the EDID, it should not be available at all (Full HD max). We will now override this EDID in the Windows Registry with the monitor's original data and also add 4K @ 60 Hz CVT-RB to the CTA-861 Extension Block.

• Please try as follows: Download the TXT file that I have attached
• After you have reopened CRU.exe and the monitor is selected at the top, click on "Import" at the bottom left.

• Close CRU with OK and restart the computer

Is 4K @ 60 Hz now available?
If not, please connect the monitor to the other USB-C port. You don't have to repeat the procedure above.

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Hi MUC,

Thanks for your reply!

Unfortunately CRU import didn't fix the issue. After restart, both USB-C sockets display the same 29/30Hz.

In CRU I see new information popping-up about my monitor.

Since you said it is not available for selection in Windows, I could try few different workarounds:

1. Set NVidia for default display. I however need Lenovo support for that, Windows/BIOS doesn't allow changes.

2. Install Windows 11

If you have another idea, please let me know,

Thanks

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In my opinion, it is probably as Scott said. The laptop only uses 2 lanes on the USB-C ports for the DisplayPort HBR2 protocol, which limits the data rate to 10.8 Gbps.

This is actually an impudence, since the manufacturers state something else.

• Lenovo: 4K @ 60 Hz
• Dell: 2 x 4K @ 60 Hz via USB-C Multi-Stream Transport (MST) Mode HBR2

It is difficult to predict whether installing Windows 11 will help.

It is also possible that Lenovo means:
4K @ 60 Hz YCbCr 4:2:0 8-bit = 8 Gbps instead of 4K @ 60 Hz RGB 8-bit = 16 Gbps
However, the YCbCr color model is not suitable for computer monitors with pixel-accurate rendering requirements.

You can still test it.

• Undo all our changes by running "reset-all.exe" from the CRU download package and then restart the computer.
• Set the following on the monitor in its On Screen Display (OSD):

If we assume that the Dell USB hub function somehow causes only 2 lanes for the DisplayPort protocol to be used by the Lenovo laptop, you can still try to connect the laptop to the DisplayPort connector of the monitor with a cable like this:

• Zeskit MAYA 8K Bi-Directional USB-C to DisplayPort 1.4 Cable
• Club 3D USB Type C Cable to DP 1.4 (CAC-1557)
• Cable Matters USB-C to DisplayPort Cable - 8K Ready (201036)
• Cable Matters Premium Braided USB C to DisplayPort 1.4 Cable (201336)

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Ok, the YCbCr didn't work as well.

Using only the display port will not give me many of the benefits from the monitor (kvm switch...)

Just hung-up my phone-call with Lenovo; they reject giving ANY assistance to a device outside of warranty, in ANY form (live-chat/call/email/forum-offline). Crazy!

Since I'm on my own, I will try two things
- to somehow switch to NVidia card for the display, after getting an Enterprise version of Windows, which would hopefully let me tweak more settings.

- to get a cable and use the side-docking-station input, which claims will use NVidia card for the displays

Many thanks for your spent effort

Cheers

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