Dual Monitors Cannot Display 4K When Connected Through a Thunderbolt Docking Station

You cannot get 4K 60 Hz resolution from dual screens through a Thunderbolt dock

You can see the following limitation if you use dual external monitors on your Precision 7670 or 7770 Mobile Workstation. The monitors cannot reach a 4K 60 Hz resolution.

You this under the following conditions:

• The dual screens are connected through a WD19TBS or WD22TB4 Thunderbolt docking station
• You are using the Red Hat Enterprise Linux operating system (Version 8.6)
• You are using two 4K capable screens:
  • Monitor 1: 1920x1080 @60 Hz
  • Monitor 2: 3840x2160 @60 Hz

The Red Hat Enterprise Linux operating system (version 8.6) cannot support High bit rate 3 (HBR3) on the Intel Alder Lake-HX (ADL-HX) core series processor.

This is a limitation of a Linux operating system on the Intel ADL-HX processor.

The following instructions are a workaround:

1. Connect your dock using the USB Type-C port.

2. Switch the graphic mode to Direct Graphics Controller Direct Output Mode:

   1. Press the power button to turn on your mobile workstation.

   2. Press the F2 key to enter the BIOS setup screen, when you see the Dell splash screen appear.

   3. Click Display.

   4. Go to Enable Hybrid Graphics which defaults to ON.

   5. Change Direct Graphics Controller Direct Output Mode from OFF to ON.

   6. Click APPLY CHANGES.

   7. Click OK.

   8. Click the EXIT button to exit the BIOS and restart into your mobile workstations operating system.

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