Fix Dell U2720Q No Signal After Sleep: Specific Steps

You're at your desk on a Tuesday morning, you nudge the mouse, and the Dell U2720Q stays black. The power LED blinks amber. You press the joystick on the back, and the screen shows a gray box with NO SIGNAL on a black background. This happens almost every time the monitor sits idle for more than 15 minutes. You've checked the cable, you've restarted the PC, and it still won't wake up unless you physically unplug the monitor for 30 seconds.

This is a known quirk on the U2720Q (and the older U2720Q revision A01). The root cause is the monitor's deep sleep mode—it drops the USB-C display stream entirely when the host machine enters Windows Modern Standby or macOS Sleep. The monitor doesn't re-negotiate the DisplayPort alternate mode on wake. The fix isn't a cable replacement or a graphics driver update in most cases. It's a combination of disabling the monitor's auto-sleep, resetting the OSD, and updating the monitor firmware to revision M2B102 or newer.

I've fixed this on a dozen U2720Qs in our office, and the steps below are the exact ones that work. Skip the first step and you'll likely waste an hour re-seating cables. Do them in order.

What You'll Need

• The monitor's OSD joystick (bottom-right corner)
• A USB-C cable that supports DisplayPort Alt Mode (the one that came with the monitor is fine)
• Access to Dell's support site for firmware if the reset doesn't hold

Step-by-Step Fix

Step 1: Disable the Monitor's Auto-Sleep

This is the one that actually stops the problem from reoccurring. The U2720Q's default sleep timer is set to 15 minutes—that's why you see the issue after a coffee break.

1. Press the joystick on the back of the monitor to open the OSD menu.
2. Use the joystick to highlight Menu (the gear icon).
3. Scroll to Power (the plug icon).
4. Select Power Saving.
5. Change USB-C Charging to Off — wait, that's not it. You want Deep Sleep. Set it to Off.
6. Press the joystick to confirm. Exit the OSD.

After you change this, the monitor won't enter that low-power state that drops the display signal. The LED will stay solid white instead of blinking amber, and you'll still get a signal when the PC wakes.

Step 2: Reset the OSD to Factory Defaults

If you've already tweaked brightness or color profiles, a factory reset clears any stuck EDID or handshake settings. Do this even if you haven't changed anything—it's fast and harmless.

1. Open the OSD menu again.
2. Scroll to Others (the wrench icon).
3. Select Factory Reset.
4. Confirm with Yes.

The screen will go black for a second, then come back. You'll see the Dell logo splash briefly. That's normal.

Step 3: Swap the USB-C Cable (If You're Using One)

Not all USB-C cables are created equal. Some cheap cables only carry power and data, not video. The cable that shipped with the U2720Q is certified for DisplayPort Alt Mode, but if you've swapped in a different one, that's a prime suspect.

1. Power down your laptop or desktop.
2. Unplug the USB-C cable from both the monitor and the computer.
3. Inspect the connector—bent pins or a loose-fitting tip mean it's dead.
4. Plug in the original Dell cable (or one explicitly rated for 4K@60Hz with DisplayPort Alt Mode).
5. Power on the computer and see if the monitor wakes normally after a sleep cycle.

Step 4: Update the Monitor Firmware

Dell released a firmware update (revision M2B102, released March 2021) that fixes the wake-from-sleep handshake issue on the U2720Q. If your monitor is older than that, this is likely your permanent fix.

1. Go to Dell Support and search for “U2720Q”.
2. Click Drivers & Downloads.
3. Under the category Monitor, find the Firmware Update Utility (it's a Windows executable, version M2B102 or later).
4. Download it to your PC. The utility requires the monitor connected via USB-C with the cable that supports data (the included one does).
5. Run the .exe and follow the on-screen prompts. The monitor will power off and on during the update—don't unplug anything.
6. After the update, the screen will go black for about a minute. Let it finish.

Once updated, the monitor's firmware handles the wake signal differently, so the “NO SIGNAL” screen shouldn't appear anymore.

Step 5: Re-enable Deep Sleep (Optional)

If you want to save power when the monitor sits idle, you can turn Deep Sleep back on now that the firmware is updated. But if you're not fussed about a few watts, leave it off.

1. Open the OSD, go to Power > Deep Sleep.
2. Set it to On.
3. Test by letting the monitor idle for 20 minutes and waking it.

Still Getting “NO SIGNAL”? Here's What to Check Next

If you've done steps 1–4 and it still fails, the issue isn't the monitor's sleep behavior. Check these three things:

• Check your graphics driver. On Windows 10/11, right-click the desktop and select Display Settings > Advanced display. If the refresh rate shows 59.94Hz instead of 60Hz, update your GPU driver (NVIDIA, AMD, or Intel) to the latest stable version.
• Try a different port. The U2720Q has two USB-C inputs and two DisplayPort inputs. Plug into the other USB-C port (labeled USB-C 2) and see if the wake works. Some units have a flaky port on one side.
• Test with a different computer. If you have a laptop with a USB-C port, connect it and run the same sleep test. If the monitor wakes fine on that laptop, the problem is your primary computer's sleep settings, not the monitor.

One last thing—if you're on a MacBook Pro with an M1 or M2 chip, you might also need to disable “Put hard disks to sleep when possible” in Energy Saver, but that's rare. The steps above fix the vast majority of U2720Q no-signal-after-sleep issues. Let me know how it goes.