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Difficulty: HardVideo, Display, and Projector Issues

A technician is setting up a dual-monitor workstation connected to a corporate laptop through a single USB-C docking station using DisplayPort Multi-Stream Transport (MST). The primary monitor operates normally at full resolution, but the second daisy-chained monitor displays an incorrect low resolution and suffers from intermittent screen flickering. Which of the following potential root causes or initial troubleshooting steps should the technician evaluate to address these symptoms? (Select TWO.)

  1. The combined resolution and refresh rate of both monitors exceed the total video bandwidth available over the single USB-C DisplayPort Alt Mode connection.Answer
  2. DisplayPort MST mode is disabled in the OSD settings of the primary monitor or unsupported by the current graphics driver configuration.Answer
  3. C
    The inverter board supplying high-voltage AC power to the secondary OLED monitor's backlight is failing and must be replaced.
  4. D
    The system's display driver has crashed due to VRAM overheating and must be uninstalled to clear persistent resolution locks.

Answer

The technician should verify that the combined monitor resolution does not exceed the USB-C DisplayPort Alt Mode bandwidth limit and ensure that DisplayPort MST mode is properly enabled in the monitor OSD and supported by the graphics driver.
DisplayPort Multi-Stream Transport (MST) requires both adequate cable/interface bandwidth and proper configuration. If the total pixel bandwidth of all connected displays exceeds the USB-C DisplayPort Alt Mode capacity, secondary monitors drop in resolution or suffer signal loss. Additionally, MST must be explicitly enabled in the monitor's OSD configuration and supported by driver software to route separate video signals.

Step-by-Step Solution

1
Analyze the physical and logical display connection topology.
The topology relies on DisplayPort Multi-Stream Transport (MST) over a single USB-C Alt Mode link.
MST enables multiplexing independent display streams over a single cable path, but total bandwidth is strictly bounded by the USB-C lanes dedicated to video.
2
Evaluate bandwidth limitations of the host interface.
Running multiple high-resolution displays exceeds total link bandwidth, causing secondary screens to fallback to lower resolutions or flicker.
Lowering resolution or refresh rate on the primary monitor frees required bandwidth for the secondary screen.
3
Verify protocol configuration on display hardware.
Disabling MST in monitor OSD defaults the connection to Single-Stream Transport (SST), mirroring displays or disabling the downstream port.
Enabling MST in the monitor settings enables proper stream routing across daisy-chained links.

Key Concept

DisplayPort Multi-Stream Transport (MST) and USB-C Video Bandwidth Troubleshooting
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Topics

Video, Display, and Projector Issues

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