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Article Number: 000181837

Key features of Dell UltraSharp U2421HE U2721DE Monitor

Summary: 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, so on see an expanding section below. ...

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Getting Started with your Product Name Product Name Setup, Specifications and Service Manual Dell Drivers & Downloads Warranty and Support Services 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, so on see an expanding section below.

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The key features of the Dell UltraSharp U2421HE and U2721DE monitor are:

  • U2421HE: 60.47 cm (23.8 in.) active area display (measured diagonally) 1920 x 1080 (16:9) resolution, plus full-screen support for lower resolutions.
  • U2721DE: 68.47 cm (27 in.) active area display (measured diagonally) 2560 x 1440 (16:9) resolution, plus full-screen support for lower resolutions.
  • Tilt, swivel, pivot, and vertical extension adjustment capabilities.
  • Extensive digital connectivity with DP helps future-proof your monitor.
  • Single USB Type-C to supply power to the compatible laptop while receiving a video signal.
  • USB-C and RJ45 ports enable a single-cable, network-connected experience.
  • On-Screen Display (OSD) adjustments for ease of set-up and screen optimization.
  • Power and OSD buttons lock.
  • Security lock slot.
  • 0.3 W standby power when in sleep mode.
  • Optimize eye comfort with a flicker-free screen.
WARNING: The possible long-term effects of blue light emission from the monitor may damage your eyes, including eye fatigue or digital eye strain. ComfortView feature is designed to reduce the amount of blue light that is emitted from the monitor to optimize eye comfort.
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 U2421HE and U2721DE monitor. To learn more about the specifications of the Dell UltraSharp U2421HE and U2721DE monitor, see the User's Guide at the Dell Manuals website.

Model U2421HE U2721DE
Panel technology
  • In-Plane Switching Technology
  • In-Plane Switching Technology
Maximum resolution
  • 1920 x 1080 at 60 Hz
  • 2560 x 1440 at 60 Hz
Viewing angle
  • 178° (vertical) typical
  • 178° (horizontal) typical
  • 178° (vertical) typical
  • 178° (horizontal) typical
Contrast ratio
  • 1000 to 1 (typical)
  • 1000 to 1 (typical)
Response time
  • 8 milliseconds (Normal)
  • 5 milliseconds (Fast)
  • 8 milliseconds (Normal)
  • 5 milliseconds (Fast)
Color gamut
  • 99% sRGB
  • 99% REC709
  • 85% DCI-P3
  • 99% sRGB
  • 99% REC709
  • 85% DCI-P3
Color depth
  • 16.7 billion colors
  • 16.7 billion colors
Ports and connectors
  • 1 x DP 1.4 (HDCP 1.4)
  • 1 x HDMI1.4 (HDCP 1.4)
  • 1 x USB Type-C (Alternate mode with DisplayPort 1.4, USB 3.1 upstream port, Power Delivery PD up to 65 W)
  • 1 x DP (Out) with MST (HDCP 1.4)
  • 2 x USB 3.0 downstream port
  • 2 x USB 3.0 with BC1.2 charging capability at 2A (max)
  • 1 x Analog 2.0 audio line out (3.5 mm jack)
  • 1 x RJ45
  • 1 x DP 1.4 (HDCP 1.4)
  • 1 x HDMI1.4 (HDCP 1.4)
  • 1 x USB Type-C (Alternate mode with DisplayPort 1.4, USB 3.1 upstream port, Power Delivery PD up to 65 W)
  • 1 x DP (Out) with MST (HDCP 1.4)
  • 2 x USB 3.0 downstream port
  • 2 x USB 3.0 with BC1.2 charging capability at 2A (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 will only help make the viewing experience the best it possibly can be.

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 U2421HE and U2721DE 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 U2421HE and U2721DE 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). Set the top edge of the screen at eye level when you are sitting comfortably. Adjust your chair height or the height of the monitor to achieve this.

Connecting your monitor to the computer

To connect your Dell UltraSharp U2421HE and U2721DE monitor to your computer:

  1. Turn off your computer and disconnect the power cable.
  2. Connect the DisplayPort, HDMI, or USB Type-C cable to the corresponding video or display port on the back of your computer. Learn How to Connect a Monitor to a Dell Computer
    NOTE Dell UltraSharp U2421HE and U2721DE supports display over USB Type-C port with Alternate mode DP 1.4. Ensure that the USB Type-C on your computer supports Alternate mode DP 1.2 or above.
  3. Connect the USB upstream cable to the monitor and computer.

Dell UltraSharp U2421HE and U2721DE 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 UltraSharp U2421HE and U2721DE should not be rotated either to 180° (landscape) or 90° (portrait).

CAUTION: Dell UltraSharp U2421HE and U2721DE 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 and/or cause a safety hazard.

When setting up your Dell UltraSharp U2421HE and U2721DE monitor, ensure that the monitor front panel buttons is on the bottom right.

Using the Tilt, Swivel, and Vertical Extension
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.

With the stand that is attached to the monitor, you can tilt and swivel the monitor for the most comfortable viewing angle.

Dell UltraSharp U2421HE and U2721DE Tilt and Swivel
Figure 1: Using Tilt and Swivel on Dell UltraSharp U2421HE and U2721DE monitor

When mounted on the wall or on a monitor arm, the set-up must comply with the recommended panel orientation and working angle.

Dell UltraSharp U2421HE and U2721DE Orientation
Figure 2: Orientation of Dell UltraSharp U2421HE and U2721DE

Dell UltraSharp U2421HE and U2721DE Dual Monitor Setup
Figure 3: Illustration of Dell UltraSharp U2421HE and U2721DE Connection

WARNING: The monitor should not be rotated 180° (landscape). The monitor should not be orientated 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 3 (Figure 4) 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 U2421HE and U2721DE 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 UltraSharp U2421HE and U2721DE Monitor Front Panel Buttons
Figure 4: Dell UltraSharp U2421HE and U2721DE Front Panel Buttons
Button Function Description
Button 1 Shortcut key: Preset Modes Use this button to choose from a list of preset color modes.
Button 2 Shortcut key for Input Source Use this button to select the input source.
Button 3 Menu Use this menu button to launch the on-screen display (OSD) and select the OSD menu.
Button 4 Exit Use this menu button to go back to the main menu or exit the OSD main menu.
Button 5 Power (with power light indicator) Use the Power button to turn the monitor On and Off. The white LED indicates that the monitor is On and fully functional.
A glowing white LED indicates DPMS Power Save Mode.

Resetting a monitor to factory defaults can help resolve many video or display issues. To reset your Dell UltraSharp U2421HE and U2721DE monitor to factory default settings, follow these instructions:

  1. Press Button 3 (Figure 4) on the monitor to enter the On-Screen Display (OSD) Menu.
  2. Press Button 1 or Button 2 (Figure 5) to select Others option in the menu and press Button 2 to select.
  3. Press Button 1 or Button 2 to select Factory Reset option in the menu and press Button 2 to select.
  4. Press Button 2 to confirm the reset action.

Dell UltraSharp U2421HE and U2721DE Monitor Front Panel Buttons
Figure 5: Dell UltraSharp U2421HE and U2721DE Front Panel Buttons.

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 will help determine if the Dell monitor is functioning normally. Learn 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 will 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.

Self-Test Feature Check

Your Dell UltraSharp U2421HE and U2721DE 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.
  4. Turn off your monitor and reconnect the video cable, then turn on both your computer and the monitor.
  5. 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.

Built-In Self-Test

Your Dell UltraSharp U2421HE and U2721DE monitor has a built-in diagnostic tool. It helps to determine if the screen abnormality you are experiencing is a problem 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. Unplug the video cables from the back of the computer or the monitor. The monitor will now enter self-test mode.
  3. On the front panel, press and hold Button 1 (Figure 6) on the front panel for 5 seconds. A gray screen appears.
  4. Carefully inspect the screen for abnormalities.
  5. Press Button 1 on the front panel again. The color of the screen changes to red.
  6. Inspect the display for any abnormalities.
  7. Repeat steps 5 and 6 to inspect the display in green, blue, black, white, and text screens.
  8. The test is complete when the white screen appears.
  9. Press Button 2 to exit the Built-In Self-Test diagnostics.
Dell UltraSharp U2421HE and U2721DE Monitor Front Panel Buttons
Figure 6: Dell UltraSharp U2421HE and U2721DE Front Panel Buttons
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 can help resolve the most common issues with the Dell UltraSharp U2421HE and U2721DE monitor. Alternatively, learn How to Troubleshoot Display or Video Issues on a Dell Monitor.

Common Problem 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 depressed fully.
  • Test with known good cable and known-good computer if possible.
No Video - Power LED On No picture or no brightness.
  • Increase the brightness and contrast of the monitor through 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 by the Input Source Select button.
  • Test monitor with the known good computer if available.
Missing Pixels LCD screen has spots.
  • Cycle power on-off.
  • A pixel that is permanently off is a natural defect that can occur in LCD technology.
  • Learn more about Dell Display Pixel Guidelines. 
Stuck-On/Off Pixels 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.
Brightness Problems Picture too dim or too bright.
  • Reset the monitor to factory settings.
  • Adjust brightness and contrast controls by OSD.
Safety-Related Issues Visible signs of smoke or sparks.
  • Do not perform any troubleshooting steps.
  • Contact Dell Technical Support immediately.
Intermittent Problems Monitor malfunctions on and off.
  • Ensure that the video cable is connected properly with the monitor and the computer.
  • Reset the monitor to the Factory Settings.
  • Run the self-test feature and determine if the intermittent problem 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 Picture color is not good.
Image Retention from a Static Image Left on the Monitor for a Long Period 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.
Screen image is too small. Image is centered on the screen but does not fill the entire viewing area.
Image Ghosting Fast-moving images leave a trail of shadow images.

On certain videos 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 to the monitor and the computer.
  • Restart the computer.
The picture does not fill the entire screen. The picture cannot fill the height or width of the screen.
  • Due to different video formats (aspect ratio) of DVDs and videos, the monitor may display on the 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.
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.
No video when the monitor is connected to a Dell docking station. The monitor may not receive video signals from the computer when connected to a Dell docking station. To learn more about how to set up and configure the Dell UltraSharp U2421HE and U2721DE monitor with a Dell docking station. See the Dell knowledge-base article How to Connect and Set Up a Docking Station With a Dell Laptop.
Light leak from the monitor The monitor appears to have a light leak from the edges in a dark room This is the 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 tighter criteria of 70-lux ambient lighting (dimly lit room but not dark).
Color variation on the corners of the monitor The monitor appears to have a color variation on the corners of the screen

The optimal viewing position for the monitor is from the center of the screen.

Dell UltraSharp U2421HE and U2721DE monitor uses a curved IPS panel, the corners of the screen may appear slightly yellowish or pinkish, especially when viewing in the darkroom. This is normal IPS panel behavior and typically does not affect the overall viewing performance.

  1. Change the Uniformity Compensation by On-Screen Display Menu (OSD).
  2. Change the Uniformity compensation setting to Calibrated.
Troubleshooting USB Issues
Specific Symptoms What User Experiences Possible Solution
USB interface is not working. USB peripherals are not working.
  • Check that your monitor is turned On.
  • Reconnect the upstream cable to your computer.
  • Reconnect the USB peripherals (downstream connector).
  • Switch Off and then turn On the monitor again.
  • Reboot the computer.
  • Some USB devices like external portable HDD require a higher electric current; connect the device directly to the computer.
THE high-Speed USB 3.0 interface is slow. High-Speed USB 3.0 peripherals 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 peripherals (downstream connector).
  • Reboot the computer.
Wireless USB peripherals stop working when a USB 3.0 device is plugged in. Wireless USB peripherals respond slowly or only work as the distance between the device and the receiver decreases.
  • Increase the distance between the USB 3.0 peripherals and the wireless USB receiver.
  • Position your wireless USB receiver as close as possible to the wireless USB peripherals.
  • Use a USB-extender cable to position the wireless USB receiver as far away as possible from the USB 3.0 port.
USB Type-C port does not supply power. USB peripherals cannot be charged.
  • Check that the connected device is compliant with the USB-C specification. The USB Type-C port supports USB 3.1 with speeds up to 10 Gbps and an output of 90 W.
  • Ensure you use the USB Type-C cable shipped with your monitor.
USB ports on the monitor do not work when the monitor is connected to a computer using USB Type-C. If the monitor is powered off and then powered on too quickly, the laptop will not recognize the computer.
  1. Power off the monitor
  2. Wait for 5 seconds.
  3. Power on the monitor
The monitor does not wake up by the USB keyboard or mouse that is connected to the monitor. In sleep mode, the monitor does not receive power to the USB 3.0 ports. Wake up the laptop computer using the built-in keyboard or touchpad

Learn how to view or download the Manuals and Documentation for your Dell Product

Additional Information

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 on the desktop and then click Screen Resolution.
  3. Click the dropdown list of the Screen Resolution and select 1920 x 1080.
  4. Click OK.

Using Nvidia Control Panel

To change the resolution using the Nvidia Control Panel:

  1. Right-click on the desktop and then click Nvidia Control Panel.
  2. Click the + symbol next to Display on the left pane.
  3. Select Change Resolution under Display.
  4. In the dropdown menu on the right pane, select the resolution 1920 x 1080.
  5. Click Apply.

Using the AMD Catalyst Control Center

To change the resolution using the AMD Catalyst Control Center:

  1. Right-click the desktop and click AMD Catalyst Control Center.
  2. Click the + symbol next to Display on the left pane.
  3. Select Change Resolution under Display.
  4. In the dropdown menu on the right pane, select the resolution 1920 x 1080.
  5. Click Apply.
NOTE: If you do not see the recommended resolution as an optio, update the video card (GPU) driver from Dell.com/support/drivers or the video card (GPU) manufacturers' website. Learn How to Download and Install Dell Drivers.

To reset the Dell UltraSharp U2421HE and U2721DE Monitor to factory defaults, see the Reset to Factory Settings section of this article.

How to Run a Diagnostic Test on a Dell Monitor

The Dell UltraSharp U2421HE and U2721DE monitor has two built-in diagnostics that are available:

  • Self-Test Feature Check - The self-test feature check on the Dell UltraSharp U2421HE and U2721DE monitor allows you to check whether the monitor is functioning properly.

  • Built-In Self-Test - The Dell UltraSharp U2421HE and U2721DE 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 U2421HE and U2721DE 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 U2421HE and U2721DE 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 3 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 U2421HE and U2721DE monitor.

USB Type-C port on your Dell UltraSharp U2421HE and U2721DE supports USB Power Delivery, Data, and DisplayPort video signal. The USB Type-C port can be used for video and data signal, and supply power (90 W) to a compatible laptop computer using a single USB Type-C cable that is provided with the monitor.

NOTE: Dell UltraSharp U2421HE and U2721DE can supply power by the USB Type-C cable only to a compatible laptop computer that supports Power Delivery (PD) over USB Type-C. Not all laptop PCs with USB Type-C support Power Delivery, for more information, see the User Manual or contact your laptop manufacturer.
NOTE: USB Type-C power delivery-compliant port (PD version 2.0) delivers up to 90 W of power. If your laptop computer requires more than 90 W to operate and the battery is drained. It is recommended you use the standard AC adapter of the laptop computer to turn on and charge the laptop battery.

If you are using a Dell laptop computer that supports charging by USB Type-C. It is recommended to update the BIOS and Video or Graphics card (GPU) driver. Learn How to Download and Install Dell Drivers.

Article Properties

Affected Product

Dell U2421HE, Dell U2721DE

Last Published Date

23 Jan 2024

Version

6

Article Type

How To

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