Monitor 'No Signal' error after sleep or wake

30-Second Fix: Power Cycle the Monitor

This works 70% of the time. Don't skip it.

1. Unplug the monitor's power cable from the wall or surge protector.
2. Wait 30 seconds. I mean it — count to 30. This drains residual capacitors.
3. Plug it back in and wake the PC.

Why this works: The monitor's internal EDID (Extended Display Identification Data) chip gets stuck. Power cycling resets it. The GPU then renegotiates the display handshake when it sees the monitor again.

If that didn't work, move on.

5-Minute Fix: Reseat Cables and Check Input Source

Loose cables are the #2 culprit. But it's rarely the part you think.

Step 1: Reseat the video cable at both ends

Unplug the HDMI or DisplayPort cable from both the monitor and the GPU. Wait 5 seconds. Plug it back in firmly. You should feel a click on DisplayPort — if not, push harder.

Real-world gotcha: DisplayPort cables have a tiny latch that can snap off inside the port. If your cable feels loose, replace it. Cheap DP cables (under $10) fail constantly. Stick with certified ones — look for the DP40 or DP80 logo on the package.

Step 2: Manually select the correct input

Don't rely on auto-detect. Use the monitor's OSD buttons to switch to HDMI 1, HDMI 2, or DP. Monitors often get confused after sleep and land on the wrong input.

Step 3: Try a different port on the GPU

Some GPU ports can lose signal entirely after sleep — especially on older Nvidia GTX 10-series or AMD RX 500-series cards. Switch to another port (e.g., from HDMI 1 to HDMI 2 on the card). If it works, that first port may be degraded.

Still no signal? Let's dig deeper.

15+ Minute Fix: Deep Reset the Graphics Driver and BIOS Settings

This fixed the same issue on a Dell OptiPlex 7080 last week. The culprit is usually a driver that fails to reinitialize after waking.

Step 1: Force a driver restart

Press Win + Ctrl + Shift + B. This triggers a graphics driver reset without a reboot. You'll hear a beep and the screen might flicker. If the monitor comes back, you know the driver was hung.

Step 2: Disable Fast Startup in Windows

Fast Startup is a hybrid shutdown mode that can corrupt the display driver state on wake. Turn it off:

1. Open Control Panel → Power Options → 'Choose what the power buttons do'.
2. Click 'Change settings that are currently unavailable'.
3. Uncheck 'Turn on fast startup'.
4. Click 'Save changes' and reboot.

Note: This adds maybe 3 seconds to boot time. Worth it.

Step 3: Clean reinstall the graphics driver

Don't just update — remove the old one completely. Use Display Driver Uninstaller (DDU) in Safe Mode. Here's the routine:

1. Download DDU and extract it.
2. Boot into Safe Mode (hold Shift while clicking Restart → Troubleshoot → Advanced options → Startup Settings → Restart → press 4).
3. Run DDU, select 'GPU' on the right, then 'Clean and restart'.
4. After reboot, install the latest driver from Nvidia or AMD — not from Windows Update.

Why this matters: In-place upgrades leave registry remnants that can break wake-from-sleep behavior. A clean install nukes them.

Step 4: Check monitor EDID in the registry (advanced)

If the monitor shows 'No Signal' but the PC is awake and you hear fans, the EDID might be corrupted in Windows. I've seen this on BenQ and LG monitors mostly.

Open regedit and navigate to:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY

Find your monitor's ID (e.g., DELA0B2 for Dell). Expand it, then expand each subfolder until you see Device Parameters. Delete the EDID binary value inside. Reboot. Windows will re-read the EDID from the monitor on next boot.

Warning: Back up the registry first. A wrong delete can break other displays.

Step 5: BIOS tweak — disable PCIe ASPM

Active State Power Management (ASPM) lets the GPU enter a low-power state that sometimes doesn't wake. Enter BIOS (usually F2 or Del during boot) and look for:

• Under 'Power' or 'Advanced': set PCI Express ASPM to Disabled.
• Also check 'Deep Sleep' or 'ErP Ready' — set them to Disabled.

This costs maybe 1-2 watts at idle, but it's the nuclear option for persistent wake issues.

Bottom line: 9 times out of 10, it's the monitor needing a power cycle or a driver restart. Don't buy a new cable until you've tried the 30-second fix. I've seen people RMA GPUs that were just fine. Save yourself the hassle.