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How to Use and Troubleshoot Dell UltraSharp U2421E Monitor

Summary: This article provides information about how to use and troubleshoot issues related to Dell UltraSharp U2421E monitor.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Instructions

U2421E

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Frequently asked questions

For help with video or display issues such as no video or no display, blank or black screen, flickering, resolution or color issues, horizontal or vertical lines, and more see an expanding section below.

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The key features of Dell UltraSharp U2421E Monitor are:

  • 1920 x 1200 (16:10) resolution, plus full-screen support for lower resolutions.
  • Tilt, swivel, pivot, and vertical extension adjustment capabilities.
  • Ultrathin bezel minimizes the bezel gap during multimonitor usage, enabling easier setup with an elegant viewing experience.
  • Extensive digital connectivity with DP helps future-proof your monitor.
  • Single USB-C to supply power to the compatible notebook while receiving a video signal.
  • USB-C and RJ45 ports enable a single-cable, network-connected experience.
  • Optimize eye comfort with a flicker-free screen minimizes hazard blue light emission.
  • Decrease in the level of hazard blue light that is emitted from the screen to make viewing more comfortable for your eyes.
WARNING: The possible long-term effects of blue light emission from the monitor may damage your eyes, including eye fatigue or digital eye strain.
WARNING: Do not mount this monitor in vertical orientation due to the risk of damaging the monitor.

This section provides some specifications of the Dell UltraSharp U2421E Monitor. To learn more about the specifications of Dell UltraSharp U2421E Monitor, see the User's Guide at the Dell Manuals website.

Table 1 - Technical specifications of Dell UltraSharp U2421E monitor.
Panel technology
  • In-Plane Switching
Maximum resolution
  • 1920 x 1200 at 60 Hz
Viewing angle
  • 178° (Vertical) typical
  • 178° (Horizontal) typical
Contrast ratio
  • 1000 to 1 (typical)
Response time
  • 8 milliseconds (Normal mode)
  • 5 milliseconds (Fast mode)
Color gamut
  • 99% sRGB/REC709 with calibration accuracy of Delta E < 2 (average)
Color depth
  • 16.78 million colors
Ports and connectors
  • 1 x DP 1.4
  • 1 x DDMI 1.4
  • 1 x USB-C (Alternate mode with DisplayPort 1.4, USB 3.2 Gen1 upstream port, Power Delivery PD up to 90 W)1 x USB-C downstream (15 W), USB 3.2 Gen1 (5 Gbps)
  • 1 x DP (Out) with MST
  • 2 x SuperSpeed USB 5 Gbps (USB 3.2 Gen1)
  • 1 x SuperSpeed USB 5 Gbps (USB 3.2 Gen1) with BC 1.2 charging capability at 2 A (max)
  • 1 x Analog 2.0 audio line out (3.5 mm jack)
  • 1 x RJ45

Ensuring that your Dell monitor is set up properly. Assembling the monitor stand and set up the monitor ergonomically. Connecting the cables and organizing them. These only help make the viewing experience the best possible.

Attaching the stand

The standard monitor stand is detached when the monitor is shipped from the factory. To learn more about attaching the standard monitor stand. See the Setting Up the Monitor section in the User's Guide of your Dell UltraSharp U2421E Monitor.
To learn how to set up any other stand with a monitor, see the respective stand setup guide for setup instructions.

CAUTION: Do not remove the monitor from the packaging box before attaching the stand.
NOTE: The Dell UltraSharp U2421E Monitor is heavy; handle with extreme care. It is recommended to have two people to lift or move this monitor.

Ergonomics

Where you put your monitor is almost as important as what model you buy. The monitor should be directly in front of you, at an arm’s length away (between 20-40 inches from your eyes). The top edge of the screen at eye level when you are sitting comfortably. You must adjust your chair height or the height of the monitor to achieve this.

Connecting your monitor to your computer

To connect your Dell UltraSharp U2421E Monitor to your computer:

NOTE: Dell U2421E supports display over USB-C port with Alternate mode DP 1.4. Ensure that the USB-C port on your computer supports Alternate mode DP 1.2 or above.

To learn more about connecting your monitor to the computer, see the Dell knowledge base article How to Connect a Monitor to a Dell Computer.

  1. Turn off your computer and disconnect the power cable.
  2. Connect the DisplayPort, HDMI, or USB-C cable to the corresponding video or display port on the back of your computer.
  3. Connect the USB upstream cable to the monitor and computer.

Dell UltraSharp U2421E Monitor orientation must always be in landscape mode. This includes any wall-mounted monitors and monitors on a stand. In a multiple monitor setup, Dell U2421E should not be rotated either to 180° (landscape) or 90° (portrait).

CAUTION: Dell U2421E setup must comply with the recommended panel orientation and working angle only. Setting up the monitor in an orientation that is not recommended may damage the monitor or cause a safety hazard.

When setting up your Dell UltraSharp U2421E Monitor, ensure that the monitor front panel buttons are on the bottom right.

NOTE: This is applicable for a monitor with a stand. When any other stand is bought, see the respective stand setup guide for set-up instructions.
WARNING: Do not rotate the monitor 180° (landscape). Do not orientate the monitor at 90° (portrait).

Use the buttons at the bottom of the monitor to access the On-Screen Display (OSD) menu of the monitor. To access the On-Screen Display (OSD) menu, press Button 5 (Figure 1) at the bottom of the monitor.

Learn more about using the On-Screen Display (OSD) menu. See the Operating Your Monitor section in the User's Guide of Dell UltraSharp U2421E Monitor.

NOTE: Any changes that you make are automatically saved. Whenever you move to another menu item, exit the OSD menu, or wait for the OSD menu to automatically close.

Dell U2421E Monitor Buttons
Figure 1: Dell U2421E Front Panel Buttons

Table 2 - Buttons on the Dell UltraSharp U2421E monitor.
Button Function Description
Button 1 Up Down Use the Up (increase) and Down (decrease) buttons to adjust items in the OSD menu.
Button 2 Previous Use the Previous button to go back to the previous menu.
Button 3 Next Use the Next button to confirm your selection.
Button 4 Tick Use the Tick button to confirm your selection.

If your Dell monitor has a blank or black screen, fuzzy or blurry image, flickering, distorted, or any other screen abnormalities, running a diagnostic test helps determine if the Dell monitor is functioning as designed. To learn more about diagnostic options on a Dell monitor, see the Dell knowledge base article How to Run a Diagnostic Test on a Dell Monitor.

It is always essential to isolate the monitor while troubleshooting your computer for the following scenarios:

  • No Power - Your computer is not powering ON or showing any signs of power.
  • No POST - Your computer is not showing any indication of activity, the screen might be blank and does not display the Dell logo during start-up.
  • No Video - You are unable to see any display on the screen, able to hear the windows chime but no display is seen.

Your Dell UltraSharp U2421E Monitor provides a self-test feature check that allows you to check whether the monitor is functioning properly. If the monitor and computer are properly connected but the monitor screen remains dark, run the monitor self-test by performing the following steps:

  1. Turn off both your computer and the monitor.
  2. Unplug the video cable from the back of the computer. To ensure proper Self-Test operation, remove the video cables (VGA, DVI, HDMI, or DisplayPort) from the back of the computer.
  3. Turn on the monitor.
    The floating dialog box should appear on-screen (against a black background) if the monitor does not sense a video signal and is working correctly. While in self-test mode, the power LED remains white. Also, depending upon the selected input, one of the dialogs that are shown below continuously scrolls through the screen.
  4. This box also appears during normal system operation if the video cable becomes disconnected or damaged.
  5. Turn off your monitor and reconnect the video cable, then turn on both your computer and the monitor.

If your monitor screen remains blank after you use the previous procedure, check your video card (GPU) and computer, because your monitor is functioning properly.

Your Dell UltraSharp U2421E Monitor has an built-in diagnostic tool. It helps to determine if the screen abnormality you are experiencing is an issue with the monitor or with the video card on your computer.

When you notice screen abnormalities like distortion, clarity, horizontal or vertical lines, color fade, it is always a good practice to isolate the monitor by running the built-in diagnostics.

  1. Ensure that the screen is clean (no dust particles on the surface of the screen).
  2. Press and hold Up or Down or Left or Right direction for four seconds until a menu appears on the screen.
  3. Using the joystick control, select the Diagnostics option and press the joystick button to start the diagnostics. A gray screen is displayed.
  4. Observe if the screen has any defects or abnormalities.
  5. Tap the joystick once again until a red screen is displayed.
  6. Observe if the screen has any defects or abnormalities.
  7. Repeat steps 5 and 6 until the screen displays green, blue, black, and white colors. Note any abnormalities or defects.
NOTE: If you do not detect any screen abnormalities upon using the built-in diagnostic tool, the monitor is functioning properly. Check the video card (GPU) and the computer.
If you notice any abnormalities during built-in diagnostics, you may get the monitor repaired or replaced if it is under warranty by contacting Dell Technical Support.

During the LCD Monitor manufacturing process, it is not uncommon for one or more pixels to become fixed in an unchanging state. Which is hard to see and does not affect the display quality or usability. For more information, see the Dell knowledge base article Dell Display Pixel Guidelines.

This section provides information about troubleshooting steps that help resolve the most common issues with the Dell UltraSharp U2421E Monitor. Alternatively, to learn more about troubleshooting common issues on Dell monitors, see the Dell knowledge base article How to Troubleshoot Display or Video Issues on a Dell Monitor.

Table 3 - Common troubleshooting steps to resolve display-related issues on Dell UltraSharp U2421E monitor.
Common issues What User Experiences Possible Solution
No Video - Power LED Off No picture
  • Ensure that the power cable connecting the monitor is properly connected and secure.
  • Verify that the power outlet is functioning properly using any other electrical equipment.
  • Ensure that the power button is pressed fully.
  • Test with known good cable and known good system if possible.
  • Ensure that the correct input source is selected in the Input Source menu.
No Video - Power LED On No picture or no brightness.
  • Increase the brightness and contrast of the monitor through the On-Screen Display Menu (OSD).
  • Perform monitor self-test feature check.
  • Check for bent or broken pins in the video cable connector.
  • Reseat both ends of the video cable.
  • Try with a known good video cable.
  • Run the built-in diagnostics.
  • Ensure that the correct input source is selected using the Input Source button.
  • Test monitor with a known good system if available.
Poor Focus Picture is fuzzy, blurry, or ghosting.
  • Reseat both ends of the video cable.
  • Try with a known good video cable.
  • Perform Auto Adjust using On-Screen Display Menu (OSD).
  • Adjust the Phase and Pixel Clock controls using On-Screen Display Menu (OSD).
  • Eliminate video extension cables.
  • Reset the monitor to Factory Settings.
Shaky or Jittery Video Wavy picture or fine movement.
  • Perform Auto Adjust using On-Screen Display Menu (OSD).
  • Adjust the Phase and Pixel Clock controls using On-Screen Display Menu (OSD).
  • Reset the monitor to Factory Settings.
  • Check for environmental factors (like fans or other sources of interference).
  • Relocate the monitor and test it in another room.
Missing Pixels LCD screen has spots.
  • Cycle power on-off.
  • A pixel that is permanently off is a natural defect that occurs in LCD technology.
  • Run the built-in diagnostics.
  • For more information about Dell Monitor Quality and Pixel Policy, see Dell Support site at www.dell.com/pixelguidelines.
Stuck On or Off Pixels The LCD screen has bright spot.
  • Cycle power on-off.
  • A few permanently bright or dark pixels are considered normal by industry standards. The exact number of pixels that are allowed varies depending on the monitor. See Dell Display Pixel Guidelines for more details.
  • Run the built-in diagnostics.
Brightness issues Picture too dim or too bright.
  • Dim or discolored video is caused by the video cable, so try reseating the cable and swapping with a known good part.
  • Reset the monitor to the Factory Settings.
  • Perform Auto Adjust using On-Screen Display Menu (OSD).
  • Adjust the Brightness and Contrast controls using the On-Screen Display Menu (OSD).
Geometric Distortion Screen not centered correctly.
When using DisplayPort input, the positioning adjustments are not available.
Horizontal or Vertical Lines The screen has one or more lines.
When using DisplayPort input, the positioning adjustments are not available.
Synchronization issues The screen is scrambled or appears torn.
  • Reset the monitor to the Factory Settings.
  • Perform Auto Adjust using On-Screen Display Menu (OSD).
  • Adjust Phase, and Pixel Clock controls using On-Screen Display Menu (OSD).
  • Perform monitor self-test feature check to determine if the scrambled screen appears in self-test mode.
  • Check for bent or broken pins in the video cable connector.
  • Restart the computer in the power safe mode.
Safety-Related Issues Visible signs of smoke or sparks.
  • Do not perform any troubleshooting steps.
  • Contact Dell Technical Support immediately.
Intermittent issues Monitor malfunctions on and off.
  • Ensure that the video cable is connected properly to the monitor and the computer.
  • Reset the monitor to the Factory Settings.
  • Run the self-test feature and determine if the intermittent issue occurs in the self-test mode.
Missing Color The picture does not have color.
  • Run the monitor self-test feature check.
  • Ensure that the video cable connecting the monitor to the computer is connected properly and is secure.
  • Check for bent or broken pins in the video cable connector.
Wrong Color The picture color is not good.
Image Retention from a Static Image Left on the Monitor for a Long Period A faint shadow from the static image appears on the screen.
  • Use the Power Management feature to turn off the monitor when it is not in use.
  • Alternatively, use a dynamically changing screensaver.
The screen image is too small. Image is centered on screen but does not fill the entire viewing area.
Image Ghosting Fast moving images leave a trail of shadow images.

On certain video and applications with fast moving images, imaging ghosting, which appears as a trailing shadow, may occur.

Change the Response Time to Fast in the Display menu.
No Input Signal when user controls are pressed. No picture, the power LED light is white.
  • Check the signal source. Ensure that the computer is not in power-saving mode by moving the mouse or pressing any key on the keyboard.
  • Ensure that the video cable is connected properly with the monitor and the computer.
  • Restart the computer.
The picture does not fill the entire screen. The picture does not fill the height or width of the screen.
  • Due to different video formats (aspect ratio) of DVDs and videos, the monitor may display in screen.
  • Run the built-in diagnostics.
Display mode changes from "Second screen only" to "Extended mode" after opening and closing the laptop LCD.

The display mode on your computer reverts to "Duplicate" or "Extend,". This depends on which was selected before you changed to "Second screen only" or "Projector only" when you close and open the laptop screen.

When you close and then reopen the lid on a laptop, the Connecting and Configuring Displays (CCD) feature in Windows automatically reverts the display mode to the last active selection. This behavior is by design in Microsoft Windows.

Switch to the display mode that you want after you close and reopen the laptop screen manually:

  1. Press the Windows logo key + P on the keyboard.
  2. Select Second screen only or Projector only mode.
Monitor does not display Blu-Ray video after the monitor is powered-off and powered-on. If the monitor is powered-off and powered-on when displaying the Blu-Ray video, the Blu-ray player may lose the data signal from the system to the monitor.
  1. Disconnect the HDMI cable.
  2. Wait for 5 seconds.
  3. Connect the HDMI cable.
When changing the monitor’s resolution from Windows Display Settings, the image quality may not be good. Windows Display Settings and the resolution settings on the laptop's video or graphics utility may not be compatible. Change the resolution using the video or graphics card (GPU) utility like Intel HD Graphics Control Panel.
Light leak from the monitor The monitor appears to have light leak from the edges in a dark room This is normal behavior of the monitor. Dell consumer monitors are inspected at 150-lux ambient lighting (similar to typical office lighting). Dell UltraSharp and Gaming monitors are inspected with a tighter criteria of 70-lux ambient lighting (dimly lit room but not dark).
Table 4 - Common troubleshooting steps to resolve USB issues on Dell UltraSharp U2421E monitor.
Troubleshooting USB Issues
Specific Symptoms What User Experiences Possible Solution
USB interface is not working. USB devices are not working.
  • Check that your monitor is turned On.
  • Reconnect the upstream cable to your computer.
  • Reconnect the USB devices (downstream connector).
  • Switch Off and then turn On the monitor again.
  • Reboot the computer.
  • Some USB devices like external portable HDD require higher electric current; connect the device directly to the computer.
SuperSpeed USB 3.2 Gen1 interface is slow. SuperSpeed USB Gen3.2 devices working slowly or not working at all.
  • Check that your computer is USB 3.0 capable.
  • Some computers have USB 3.0, USB 2.0, and USB 1.1 ports. Ensure that the correct USB port is used.
  • Reconnect the upstream cable to your computer.
  • Reconnect the USB devices (downstream connector).
  • Reboot the computer.
Wireless USB devices stop working when a USB 3.0 device is plugged in. Wireless USB devices responding slowly or only working as the distance between itself and its receiver decreases.
  • Increase the distance between the USB 3.0 devices and the wireless USB receiver.
  • Position your wireless USB receiver as close as possible to the wireless USB devices.
  • Use a USB-extender cable to position the wireless USB receiver as far away as possible from the USB 3.0 port.
USB is not working. No USB functionalities.
  • See input source and USB pairing table.

To learn more about how to view or download the User Guides and Manuals for your Dell product. See the Dell knowledge base article Manuals and Documentation for your Dell Product.


Frequently asked questions

Using Windows Display Settings

In Windows 10, Windows 8 or 8.1 and Windows 7:

  1. For Windows 8 and Windows 8.1 only, select the Desktop tile to switch to classic desktop view.
  2. Right-click the desktop and click Display Settings or Screen Resolution.
  3. Select the display.
  4. Click the dropdown list of the Screen Resolution and select 1920 x 1200.
  5. Click OK.
NOTE: If you do not see the recommended resolution as an option. You must update the video card (GPU) driver from the Dell Drivers & Downloads website or the video card (GPU) manufacturers website. To learn how to download and update a device driver, see the Dell knowledge base article How to Download and Install Dell Drivers.

Resetting a monitor to factory defaults can help resolve many video or display-related issues. Reset your Dell UltraSharp U2421E monitor to factory default settings by following these steps:

  1. Press Botton 5(Figure 1) on the monitor to enter the On-Screen Display (OSD) Menu.
  2. Use the joystick control on the rear of the monitor to adjust the display settings.
  3. Select Others, go to Factory Reset.
  4. Press Button 5 to confirm the reset action.
Dell UltraSharp U2421E Monitor
Figure 1: Back view

The Dell UltraSharp U2421E Monitor has two built-in diagnostics that are available:

  • Self-Test Feature Check - The self-test feature check on the Dell UltraSharp U2421E Monitor allows you to check whether the monitor is functioning properly.
  • Integrated Self-Test - The Dell UltraSharp U2421E Monitor has a built-in self-test that helps you identify if the screen abnormality is with the monitor or the video card (GPU) on your computer. When you notice screen abnormalities like distortion, clarity, horizontal or vertical lines, color fade. It is always a good practice to isolate the monitor by running the built-in diagnostics.

To learn how to run a diagnostic test, see the Running diagnostics on Dell UltraSharp U2421E Monitor section of this Dell knowledge base article.

The troubleshooting section of this Dell knowledge base article provides information about troubleshooting common issues with the Dell UltraSharp U2421E Monitor. The section has troubleshooting steps on how to resolve power issues, video issues, color or clarity issues, distortion issues, horizontal or vertical lines, brightness issues or pixel issues and so on.

To navigate the On-Screen Display (OSD) menu, use the buttons on the monitor. The monitor control buttons are usually on the right side, either on the side, front, or bottom of the monitor. To access the On-Screen Display (OSD) menu, press Button 5 on the monitor.

For more information about using the On-Screen Display (OSD) menu and different menu options. See the Operating Your Monitor section in the User's Guide of your Dell UltraSharp U2421E Monitor.

Affected Products

Dell U2421E
Article Properties
Article Number: 000181443
Article Type: How To
Last Modified: 02 Feb 2024
Version:  7
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