You're sitting there, and suddenly your main monitor blinks out for a second. Or it starts flickering like a strobe light, especially after waking from sleep or when you switch games. This is the classic DisplayPort black-screen or flicker issue. It's not your monitor dying. It's almost always a handshake problem between the GPU and the monitor over that DisplayPort connection.
The culprit here is almost always one of three things: a crappy DisplayPort cable, Display Stream Compression (DSC) glitching on high-resolution or high-refresh-rate monitors, or the GPU driver choking on the signal. I've fixed this exact issue on LG 27GN950s, Samsung Odyssey G7s, and Dell U2720Qs. The fix varies, but the process is the same every time.
What's actually causing it?
DisplayPort transmits data in packets, and the monitor and GPU negotiate the link on every handshake. When you've got a 4K monitor running at 144Hz or 1440p at 240Hz, you're pushing massive bandwidth. To cope, the GPU uses DSC, which compresses the signal. If the cable is cheap or marginal, the link drops packets, and the monitor blanks out or flickers. Also, some monitors and GPUs have bugs where the DSC negotiation fails on wake — that's the black screen you see once or twice a day.
Don't bother with HDMI unless you're switching cables anyway. HDMI 2.1 is more forgiving, but DP is what you want for high refresh rates. The real fix is proper troubleshooting, in this order.
The fix: Step by step
- Replace the cable first. This might sound too easy, but I've seen dead-on-arrival DisplayPort cables from the box. You need a VESA-certified DP 1.4 cable, preferably short (under 6 feet). Try the cable from a different monitor if you've got one. If the flicker stops, you found your problem.
- Disable DSC if you can. On Nvidia, open the NVIDIA Control Panel, go to Change resolution, select your monitor, and look for a checkbox that says Enable Display Stream Compression. Uncheck it and apply. On AMD, it's trickier — you might need to lower the refresh rate to 120Hz, which often bypasses DSC entirely. On LG monitors, the OSD has a setting called DisplayPort Version — try switching from 1.4 to 1.2. That forces DSC off.
- Update your GPU driver. Sounds generic, but I've seen driver versions with known DP bugs. For Nvidia, use the regular Game Ready driver, not the Studio driver. For AMD, use the latest Adrenalin. Do a clean install with DDU (Display Driver Uninstaller) if you've never done one — it removes old fragments that mess with link training.
- Change the DP version in the monitor OSD. If your monitor has a setting for DP 1.1/1.2/1.4, drop it to 1.2. This limits bandwidth but kills flicker in many cases. On 4K 144Hz, you lose the ability to run 144Hz, but if you're at 120Hz, you're fine.
- Adjust the refresh rate. Drop from 144Hz to 120Hz, or from 240Hz to 144Hz, and see if the flicker stops. If it does, you've confirmed it's a bandwidth/DSC problem. Then you can decide if the cable replacement fixes it.
What if it still happens?
If you've done steps 1 through 5 and you still get random black screens, look at these:
- Check your GPU's power settings. In Windows, go to Settings > System > Power & sleep > Additional power settings, then set the PCI Express Link State Power Management to Off. That's a known fix for black screens on wake.
- Try a different port on the GPU. If you have two DisplayPort outputs, plug into the other one. Some ports share lanes and cause issues.
- Disable HDCP if your monitor has that option. It's rare, but some monitors negotiate HDCP poorly over DP.
- Test with another device. Plug the monitor into a laptop or console if possible. If it's still flickering, it's the monitor's board. If it's fine, it's your GPU or cable.
One last thing: don't waste money on $80 certified cables if you're on a budget. A decent $15 cable from a brand like Cable Matters or Anker with the DP logo on the package works. But if you're running 4K 144Hz, don't buy the $4 Amazon Basics one. I've seen those fail within a week.
The bottom line: start with the cable, then DSC, then the driver. Nine times out of ten, it's the cable or the DSC setting. And if you're on a multi-monitor setup, check if the flicker follows the cable when you swap ports — that's the fastest way to nail it.