External Display Blacks Out for 30 Seconds After Changing Refresh Rate

Summary: Learn about external monitors displaying a black screen after changing the refresh rate on a Latitude or Precision laptop, and the monitor is connected to a dock using the USB Type-C Multi-Function DisplayPort (MFDP). ...

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Symptoms

Affected Products:

  • WD19
  • WD19TB
  • WD19DC
  • WD22TB4

Affected Platforms:

  • Latitude 5340
  • Latitude 5540
  • Latitude 7340
  • Precision 3580
  • Precision 3581

Connect Multi-Stream Transport (MST) and Display Stream Compression (DSC) monitor to WD19, WD19TB, WD19DC, or WD22TB4 USB Type-C Multi-Function DisplayPort (MFDP). The monitor may only show the display after 30 seconds, when changing the refresh rate.

USB Type-C MFDP connection on WD19 Series and WD22TB4 docks

Cause

Parade PS8469 has a limitation on 8 and 10 bits of interalignment feature, which sends the wrong FEC protocol to the monitor which causes the issue to occur.

Resolution

Use either full-size DP1.4 port connection for monitors that are using MST. Also, when connecting DSC monitors with MST capability to the USB Type-C MFDP disables MST in the monitor on-screen display (OSD) menu options.

Disabling MST in the monitor OSD menu

Affected Products

Dell Dock WD19, Dell Performance Dock - WD19DC, Dell Thunderbolt Dock - WD19TB, Latitude 5340, Latitude 7340, Latitude 5540, Precision 3580, Precision 3581, Dell Thunderbolt Dock – WD22TB4
Article Properties
Article Number: 000210214
Article Type: Solution
Last Modified: 29 Jul 2025
Version:  5
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