Frame Skipping Test
Photograph a moving grid to look for dropped frames on an overclocked or high refresh rate screen, and run a 10 second count of frames the browser presented.
Camera photo test
- Go full screen (or keep the grid large) and turn room lights down.
- On your phone use Pro or manual mode and set the shutter to 1/10 s (1/15 or 1/8 also work). Low ISO, focus on the screen.
- Hold the phone steady and take a few photos of the grid.
- Look for one continuous run of lit cells. Repeat at each refresh rate you want to check, such as your overclock.
Software check: dropped frames in the browser
Counts frames the browser presented for 10 seconds. A gap longer than 1.5 times the median gap is a skip in that stream. A busy main thread can cause skips even when the monitor is fine, and zero skips do not mean the panel never drops a frame. Keep this tab in front and the mouse still.
This catches frames the browser or GPU failed to deliver. It cannot see a monitor that receives every frame and then silently drops some: the browser still reports the full rate. Only the photo test above catches that.
Does your monitor show every frame it is sent?
What frame skipping is
A monitor can accept a signal at one rate and display another. An overclocked 60 Hz panel set to 75 Hz may take all 75 frames per second from the GPU but only scan out 60, throwing away every fifth frame. Windows, the GPU driver and the refresh rate test all still say 75 Hz, so you get no warning. What you see is motion that stutters in a regular rhythm and feels no smoother than 60 Hz, or worse.
Cheap 75 Hz and 100 Hz screens
Does your screen do what the box says? Some budget monitors and laptops list 75 Hz or 100 Hz because the scaler board accepts that signal, while the panel behind it keeps running near 60. Run the photo test at the advertised rate the day it arrives. A clean run means the panel showed the cells the browser presented during that exposure. It does not prove the panel never skips. A regular dark gap, while the browser rate matches the mode you set, is a sign the panel may be dropping frames. A hitch in the browser can leave a gap too, so take more than one photo.
Overclocking a monitor safely
Use Custom Resolution Utility (CRU), the NVIDIA Control Panel custom resolution screen or AMD Custom Resolutions. Step up 2 to 5 Hz at a time, keep the native resolution, and try reduced blanking timings if a step fails. Run this test after every step, not just at the end. Watch for flicker, colour banding or a blank screen, which Windows reverts after 15 seconds. Small overclocks rarely harm a panel, but they may void the warranty.
How to fix frame skipping
Lower the custom rate until the photo shows an unbroken run, then keep that one. Try DisplayPort instead of HDMI, a shorter or certified cable, and turn off the monitor's own overdrive or eco modes. If a regular gap remains at the stock rate, update the monitor firmware and GPU driver. If the gap stays and the browser rate matches that mode, the panel may not be showing every frame it is sent. After that, check smearing with the monitor ghosting test.
Related tools
- Refresh Rate Test: confirm the rate your system is sending in Hz.
- Monitor Ghosting Test: check motion blur and overdrive trails.
- FPS Test: compare 30, 60 and higher frame rates side by side.
Frequently asked questions
What is a skipped frame?
A skipped frame is a missing step in the sequence. This page lights one grid cell per frame the browser presents. In a slow photo, those cells should form one solid run. A regular dark gap in that run is a frame that was not shown. In the 10 second check, a gap much longer than the median gap counts as a skip among frames the browser presented.
Why does a background tab not count?
Browsers slow or stop animation frames while a tab is hidden. That pause is not the monitor dropping frames. This page does not add hidden time to the live rate: the first frame after you return only restarts the clock. The 10 second check stops if you leave the tab, and you run it again with this tab in front.
How far can a monitor overclock go?
Only as far as the panel still shows every frame it is sent. A custom mode can raise the signal rate while the panel keeps scanning at a lower one. Step up a few hertz at a time, keep the native resolution, and take the photo after each step. When a regular gap shows up and the browser rate matches the new mode, stop and go back to the last clean rate. An overclock can void the warranty.
Does zero skips mean the panel never drops a frame?
No. The 10 second check counts frames the browser presented, not frames the panel drew. A result of zero only means those presented frames were evenly spaced. The panel can still throw frames away after it receives them. Use the photo test for that, and one clean photo is one moment, not a guarantee.
Does a skip mean the monitor is broken?
No. The browser drops frames when the main thread is busy, power saving is on, or another tab is working. Close other work, keep the mouse still, and run the check again. Treat a regular gap in the photo, while the browser rate matches the mode you set, as a sign the panel may be skipping. It is not proof on its own.
What shutter speed should the photo use?
About 1/10 of a second. 1/15 or 1/8 of a second also work. Use a low ISO, dim the room, and hold the phone still. The readout estimates how many lit cells a 1/10 second photo should contain at the current browser rate.
Why can the browser rate and the photo disagree?
The browser rate is how often this page is asked to paint. The photo is what the panel displayed during the shutter. If the rate looks steady but the photo has a regular gap, the panel may be dropping frames the computer already sent. If both look uneven, the browser likely missed the paints, so sort that out before you blame the screen.