The first case is that your graphics card only supports this refresh rate; The second case is that you have increased the resolution of the computer, and your graphics card only supports this refresh rate at this resolution. In this case, you can change the refresh rate by setting the resolution to the default or lowering it a little; The third situation is that you have not installed the graphics card driver normally. Right click My Computer/Properties/Hardware/Hardware Manager to check whether there is a problem with the graphics card installation. If there is, reinstall the graphics card driver.(End)
