The modification method described below only includes editing the Windows registry, so there is no need to run any third-party applications of unknown origin.
In theory, this modification method will have nothing to do with the display driver/adapter because it modifies the display setting value rather than the display driver/adapter itself.
Important: Before modifying, please make sure that your monitor supports the refresh rate at the resolution you wish to use! You will bear the consequences at your own risk!
Assuming you have installed your monitor correctly (the monitor driver supports the vertical refresh rate you want, in this case 75Hz), and yours is a "normal" system (no multi-monitor support is enabled, etc.), please do as follows:
Open the Registry Editor and look for this key:
[HKEY_LOCAL_MACHINE\\system\\CurentControlSet\\Control\\Class]. Expand the Class keys and you will see a set of keys similar to {1113E534-EAF87542...}.
If you select one of them, you will see some value, which is a string called "default" or "Class", or both. They are used to identify devices, like "modem", "keyboard", and so on. Find the key with the value of "Class" to "Monitor".
Expand the key, and it should contain at least one subkey under it, usually "0000". If there are multiple subkeys, you have to see which one is currently in use and then modify it one by one.
Expand the "0000" key, which should contain the subkey "MODES" below, and then expand it, and you should see a subkey named after the maximum resolution of your monitor. Now, if you want to set the vertical refresh rate of 75Hz at 1024X768 resolution, you can add a subkey "1024,768" under the "MODES" key and add the string value "Mode1"="75-75,75-75".
Now if you open "Show Properties" (right-click on your desktop), click the "Advanced" button and go to the "Monitor" tab, you will be able to select the only refresh rate of 75Hz. Of course, the prerequisite is that the "0000" key is the key currently in use, and the "Hide modes that this monitor cannot display" option has been selected. Repeat the above modification process to add all the refresh rate/resolution combinations you want to use.
Finally, go to "Display Properties -> Advanced -> Monitor", select Refresh Rate, here select 75Hz.
Essentially, this modification is to set the minimum refresh rate that your monitor supports to the refresh rate you want to use. All games will now run at specified refresh rates, regardless of whether they are using Direct3D or OpenGL.