Flickering Video on Dell Gaming or Alienware Monitors
If you are using a Nvidia graphics card and G-Sync is turned on but your monitor is NOT G-Sync Compatible, flicker can occur. List of Dell FreeSync Gaming Monitors that are G-Sync Compatible can be found here: Dell AMD FreeSync Monitors that are Nvidia G-Sync Compatible Either turn off G-Sync or use FreeSync with an AMD graphics card.
Note: Dell Gaming monitors using a vertical alignment (VA) panel are S2721HGF, S2422HG, S2722DGM, S3222DGM, S3222HG, and S3422DWG. All these monitors, except S2721HGF, are NOT G-Sync Compatible. Because of this, flicker is expected if G-Sync is turned on. To fix this issue, either turn off G-Sync or use FreeSync with an AMD graphics card.
Run the monitor Built-in Self-Test (BIST): How to Run a Diagnostic Test on a Dell Monitor If the BIST passes, the issue is NOT with the monitor. Check your system (BIOS, graphics card, drivers, etc).
Update the graphics card driver and firmware to the latest version.
Change the cable connecting the monitor to the computer. A defective cable can cause the signal to break while being transmitted across the wire.
If the monitor has an Overclock feature and it is turned on, try to turn it off. Operating the monitor at a refresh rate higher than the panel specification can cause flicker.
If the monitor has a Moving Picture Response Time (MRPT) or Ultra Low Motion Blur (ULMB) feature and it is on, try to turn it off.
Check the surroundings. Electromagnetic fields can cause screen flickering. If there is another device plugged into the same power strip as the monitor, try to remove it.