Screen flickering is a common but often misunderstood issue that users may experience when operating displays at a refresh rate below 120Hz. As screen technology has evolved, the demand for higher refresh rates has increased, largely due to improvements in user experience, reduced eye strain, and the precision required in gaming and professional work. Understanding why flickering happens, especially at refresh rates under 120Hz, can help users make informed choices about their display settings and identify appropriate solutions.
Contents of Post
TL;DR
Screen flickering under 120Hz is typically caused by limitations in how quickly a screen refreshes to display new content. At lower refresh rates, flickering becomes more noticeable, especially under artificial lighting or to sensitive individuals. This can also be exacerbated by hardware compatibility issues or outdated drivers. Increasing your screen’s refresh rate, enabling adaptive sync technologies, or updating your system can often resolve the issue.
What Is Screen Refresh Rate?
The refresh rate of a display refers to how many times per second the image on the screen is updated or redrawn. Measured in Hertz (Hz), a refresh rate of 60Hz means the screen refreshes 60 times per second. While 60Hz used to be the standard, screens with 75Hz, 90Hz, 120Hz, and even higher refresh rates are now commonly available.
Lower refresh rates can lead to noticeable flickering, especially when the refresh rate does not align well with the content or lighting conditions. This flicker can cause eye strain, headaches, and an overall uncomfortable viewing experience for users.
Why Screen Flicker Occurs Below 120Hz
There are several technical and environmental reasons why screens might flicker more frequently at refresh rates below 120Hz:
- Perceptible Frame Intervals: At 60Hz, there’s a 16.67 millisecond delay between frames. For perceptive users, especially in bright environments or during fast motion, this can appear as noticeable flicker.
- PWM (Pulse Width Modulation): Many monitors and laptops use PWM to control brightness. PWM involves rapidly turning the backlight on and off, which can be more noticeable at lower refresh rates.
- Electrical Noise or Interference: Poor electrical shielding or grounding in a display can cause transient flickering, which stands out more at lower refresh rates.
- GPU and Display Out-of-Sync: When the graphics card output doesn’t match the screen’s refresh rate, it can lead to frame tearing or flickering — issues resolved more effectively at higher refresh rates.
At refresh rates of 120Hz or more, the interval between frames decreases significantly, making transitions smoother and flicker virtually unnoticeable to the human eye.
Key Causes of Flickering at Lower Refresh Rates
1. Pulse Width Modulation (PWM)
Industries often use PWM to manage screen brightness, especially in LCD screens. At low brightness levels, the modulation is more aggressive, turning the backlight off and on rapidly. If the refresh rate is also low, the compounding effect can lead to perceptible flicker.
Fix: Some high-end monitors provide a “flicker-free” setting or use DC dimming, which avoids PWM altogether. Also, increasing screen brightness can reduce the impact of PWM, although this may come at the cost of eye comfort or battery life.
2. Mismatched GPU Output vs. Monitor Refresh Rate
When your graphics card renders more frames than your monitor can display (e.g., GPU at 120FPS on a 60Hz screen), screen tearing occurs. Combined with flickering, this leads to an unstable viewing experience.
Fix: Enable technologies such as VSync, FreeSync (for AMD), or G-SYNC (for NVIDIA). These sync the graphics card’s output with your monitor’s refresh capability, reducing screen artifacts and flickering.
3. Outdated or Incompatible Graphics Drivers
Driver issues can lead to poor communication between your operating system, GPU, and display. When frame pacing is not synchronized properly, especially at lower refresh rates, flickering can occur randomly.
Fix: Update your graphics drivers regularly from the official website of your GPU manufacturer (NVIDIA, AMD, or Intel). Updating your operating system and ensuring your monitor’s firmware is up-to-date can also help reduce flickering.
4. Loose or Damaged Display Cables
A compromised HDMI, DisplayPort, or VGA cable can cause flickering that might be mistaken for a refresh rate issue. The lower the refresh rate, the more visible this kind of interference may become.
Fix: Replace or reseat the display cable. Use high-quality certified cables if possible, especially for 4K or high-refresh-rate monitors. Avoid using adapters unless absolutely necessary.
5. Electrical Interference and Environmental Conditions
Nearby power sources or low-quality power supplies can introduce electromagnetic interference. Fluorescent lighting operating at similar frequencies to your display can also cause visible flickering.
Fix: Use surge protectors or line conditioners for your PC setup. Turning off overhead fluorescent lights or moving your setup can sometimes solve the problem as well.
Symptoms That Suggest Low Refresh Rate Issues
Flickering may not always indicate a refresh rate problem, so it’s essential to recognize the telltale signs:
- Gradual eye fatigue during extended screen time
- Headaches after short periods of concentration
- Visible flicker during scrolling or fast video playback
- Screens that dim and brighten intermittently
If these symptoms appear more frequently at lower brightness or when performing motion-intensive tasks, it’s likely that refresh rate is a primary contributing factor.
How 120Hz and Higher Improves Stability
Switching to 120Hz or higher refresh rates has several measurable benefits:
- Reduced Flicker: Faster refresh intervals mean fewer chances for visible flicker to occur.
- Improved Motion Clarity: Greatly enhances the responsiveness of menus, scrolling, and animations.
- Lower Eye Strain: Especially for users who spend hours in front of screens, higher refresh rates can substantially reduce fatigue.
- Better Gaming and Content Creation Performance: Higher refresh rates ensure smoother gameplay and more precise editing in professional applications.
Today, many smartphones, monitors, and laptops come with 120Hz or 144Hz options. They are no longer limited to gaming equipment but are becoming mainstream for general productivity and user wellness.
How to Change and Test Refresh Rates
To change and verify your monitor’s refresh rate:
- Windows: Go to Settings > System > Display > Advanced display settings, select your monitor, and choose the maximum supported refresh rate.
- macOS: Go to System Settings > Displays, hold Option and click Scaled to view more refresh rate options.
- Third-Party Tools: Software like Custom Resolution Utility (CRU) on Windows gives fine-tuned control over refresh rate output.
After setting the refresh rate, you can validate screen stability using online motion test tools or software like UFO Test to observe for signs of screen tearing or flickering.
Conclusion
Flickering at refresh rates below 120Hz is a technical challenge stemming from both hardware and software limitations. As technology advances and higher refresh rates become more accessible, these issues become easier to mitigate. Recognizing the symptoms early, understanding their root causes, and applying the right fixes — whether it be updating drivers, changing cables, or upgrading your monitor — can make a significant difference in your viewing comfort and productivity.
If you’re frequently noticing screen flicker, especially when working long hours in front of a display, considering a monitor with a refresh rate of 120Hz or higher isn’t just a luxury — it’s quickly becoming a necessity.