Causes
- Input source does not match the cable being used — the Q27G2 has DisplayPort, two HDMI 2.0 inputs, and VGA. If the active input in the OSD is, say, HDMI while your PC is connected to the DisplayPort (or vice versa), the panel shows "No Signal" even though the PC and monitor both work. This is the most common and simplest cause of the black screen on this model.
- Loose, bent, or damaged cable — the Q27G2 needs a solid link to carry 2560x1440 at 144Hz. A connector that is only partially seated, a kinked or worn cable, or a damaged DisplayPort latch drops the signal entirely and leaves the monitor reporting no input.
- Cable plugged into the motherboard instead of the graphics card — if your CPU has integrated graphics, plugging the DisplayPort/HDMI cable into the rear motherboard ports means the discrete GPU's signal is never sent to the monitor. A common build mistake that produces an instant "No Signal" screen.
- DisplayPort handshake failure on boot or wake-from-sleep — this VA panel over DisplayPort is prone to the DP re-enumeration issue: after waking the PC from sleep, or on some boots, the monitor stays black with the power LED showing no signal until the link is re-detected. HDMI is generally more forgiving, and swapping inputs or power-cycling the monitor re-establishes the handshake.
- A resolution or refresh the link cannot carry — if a 144Hz / 1440p mode is set over a marginal or low-quality cable (or the wrong port on an older GPU), the panel can go black because the link cannot sustain the mode. This can also happen right after enabling 144Hz.
- PC-side boot failure — a PC that fails to POST (loose RAM, cleared/reset CMOS, a crashed driver) sends no video, so the otherwise-fine monitor reports "No Signal."
How to Fix
- Power-cycle in the correct order — turn off and unplug both the monitor and the PC, wait about 30 seconds, plug both back in, and switch the monitor on first, then the PC. The power LED on the Q27G2 glows white when it has signal and dark orange when it has lost it, so use this to confirm whether the monitor is actually receiving input while you work through the other steps.
- Select the correct input source in the OSD — press the joystick/menu button on the Q27G2 and cycle the Input Select to the entry matching the cable you are using (DisplayPort / HDMI 1 / HDMI 2 / VGA). If your PC is on the DisplayPort but the monitor is set to HDMI, this immediately restores the picture.
- Reseat and check the cable — power down, remove the cable from both ends, inspect for bent or missing pins, and re-seat it fully (the DisplayPort connector must click into its latch). Try the other DisplayPort/HDMI input and, if possible, a different known-good cable to rule out damage.
- Plug into the graphics card, not the motherboard — connect the DisplayPort/HDMI cable to a rear port on your discrete GPU (not the motherboard video ports if you have a separate card), and confirm the GPU is seated and receiving power so it is actually outputting signal.
- Recover a black screen after wake-from-sleep — if the monitor is black after the PC wakes, power-cycle the monitor (unplug 30s) or press Win+P on Windows twice to re-project and re-trigger the display handshake. Capping the PC not to blank/media-out at idle, or switching to the HDMI input, avoids the recurring handshake drop on this panel.
- Lower the resolution or refresh temporarily — if the screen went black right after you enabled 144Hz or a high refresh, boot the PC (Safe Mode if needed), return the display to 60Hz at a lower resolution, reboot, then reapply 144Hz only with a good cable. If the panel has no picture on any input, test it on another PC, laptop, or console — that tells you whether the fault is the monitor or the computer.
- Check the PC if it is not posting — if the Q27G2 still reports no signal and the PC shows no other signs of life, reseat the RAM, and if you recently changed BIOS settings, clear the CMOS so the machine can boot and output video. If the monitor never displays on another working device either, the panel or board is faulty and it should be handled under warranty.