Monitor Refresh Rate Test
Detect your monitor's actual refresh rate. Make sure your 144Hz or 240Hz monitor is actually running at its full speed.
Is My Monitor Running at Its Full Refresh Rate?
A common issue is having a high-refresh monitor but it is not actually enabled. Check: Windows Display Settings → Advanced display → Refresh rate. Make sure it matches your monitor's spec. Also verify your cable - HDMI 1.4 caps at 60Hz at 1080p, while DisplayPort or HDMI 2.0+ supports 144Hz and above.
Step-by-step instructions are in how to check Hz on your monitor and how to increase monitor refresh rate. To see whether your GPU actually delivers matching frames, run the FPS test, and read FPS vs refresh rate explained for how the two work together. A faster screen also makes every click count, so test your click speed with the CPS tester.