Fix 'Input Signal Out of Range' on Dell U2723QE at 4K 60Hz

When this error hits

You're running a Dell U2723QE at its native 3840x2160 resolution with a refresh rate of 60Hz. The monitor was working fine yesterday. Today you boot up Windows and get a black screen with this message floating in the middle: Input Signal Out of Range. No image, no cursor, just that white text on a black brick wall.

This usually happens after a GPU driver update, a Windows feature update, or when you plug into a different port on the same graphics card. I've also seen it when switching from DisplayPort to HDMI on an NVIDIA RTX 3060 or AMD Radeon RX 6700 XT. The monitor insists the signal is invalid, even though the resolution and refresh rate haven't changed from the ones that worked yesterday.

I know this error is infuriating. It makes you think your expensive monitor just died. It hasn't.

Root cause in plain English

The U2723QE uses a panel timing standard called CVT-RB (Coordinated Video Timing – Reduced Blanking). Most modern GPUs output that by default over DisplayPort and HDMI 2.0. But some GPU drivers — especially after an update — switch to a different timing standard, like CVT (without reduced blanking) or even a custom VESA timing. When the monitor receives a signal that doesn't match its expected reduced-blanking timings, it throws the middle finger and says Input Signal Out of Range.

It's not a bad cable. It's not a dead HDMI port. It's a handshake problem between the GPU's pixel clock and the monitor's timing table. And you can overpower it from the GPU driver.

The fix — three steps

Skip the cable swap. That's the first thing everyone tries and it almost never works for this specific error. Instead, force the GPU to use the monitor's preferred timings.

Step 1: Boot into Safe Mode

1. If you can see the screen during POST (the Dell logo), spam the F8 key or hold Shift while clicking Restart from the lock screen. If you can't see anything, power cycle three times: hold the power button down until the PC turns off, turn it back on, and when Windows starts loading, hold the power button again to force a shutdown. Do this three times. On the fourth boot, Windows will show the Automatic Repair screen.
2. Click Advanced options → Troubleshoot → Advanced options → Startup Settings → Restart.
3. After the restart, press 4 or F4 to boot into Safe Mode with Networking.

Step 2: Delete the bad driver profile

In Safe Mode, the GPU driver runs in a stripped-down state. The error won't appear. You'll see your desktop at a low resolution, probably 1024x768. That's fine.

1. Right-click the desktop and open Display Settings.
2. Scroll down to Advanced display.
3. Click Display adapter properties for Display 1.
4. In the Adapter tab, click Properties.
5. Go to the Driver tab and click Roll Back Driver. If that's greyed out, go to Uninstall Device and check Delete the driver software for this device, then click Uninstall.

This clears any corrupted timing profile.

Step 3: Set a custom resolution with CVT-RB timing

Now reboot normally. Windows will reinstall a generic driver. Once you're back to your normal desktop at 1920x1080 (or whatever it picks), do this:

1. Open NVIDIA Control Panel (or AMD Radeon Software → Display).
2. Under Display, click Change resolution.
3. Click Customize then Create Custom Resolution.
4. Set the horizontal pixels to 3840 and vertical lines to 2160.
5. Set refresh rate to 60 Hz.
6. For the timing standard, pick CVT-RB (or CVT Reduced Blanking). In NVIDIA, it's a dropdown labeled Timing. In AMD, it's under Timing Standard.
7. Click Test. You'll get a brief black screen. If it doesn't come back, don't panic — wait 15 seconds and it will revert. If it works, click Yes to keep it.

That's it. The monitor will now accept the signal because you're speaking its native timing language.

If it still fails

Two things to check:

• Your cable — even though I said it's rarely the cable, some cheap HDMI 2.0 cables can't push 4K/60Hz at full bandwidth. Try a certified Premium High-Speed HDMI cable or a DisplayPort 1.4 cable. But honestly, I've only seen this once in two years of support.
• Monitor firmware — Dell released firmware M2T102 for the U2723QE in late 2023 that improved EDID timing negotiation. Check your monitor's firmware under Menu → Others → Display Info. If it's older than M2T102, download and apply the update. It takes five minutes and fixes this permanently for most people.

I once spent two hours swapping cables and reinstalling drivers before I remembered the CVT-RB trick. Don't be me. Force the timing and move on with your life.