Powerstrip won't work. But this registry hack will:
Search for the monitor description key in your registry. It should be under HKEY_LOCAL_MACHINE\SYSTEM. The key itself begins with "Mode1" so search for that to simplify things.
*EXAMPLE*
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\...\0000\MODES\1600,1200]
"Mode1"="30.0-100.0,0.0-140.0,+,+"
Now, to set it for a minimum refresh of 75, change the first O after the comma to 75 in the "mode1" string
*EXAMPLE*
"Mode1"="30.0-100.0,75.0-140.0,+,+"
It will now use 75 for the default refresh for everything, D3D and OpenGL. You can set the minimum higher if you know what your monitor can handle.
The only downside is the key required might not exist with the "default monitor" automatically installed on some systems so update your monitor drivers if needed.