CVar gxRefresh

This cvar controls your VSync refresh rate - aka your max FPS while VSync is on. This CVar will change itself to match your monitor's refresh rate the first time you launch wow.

Default Setting

 * 75

Possible Settings
You generally don't wish to change this setting as wow will usually auto-detect this correctly.
 * 60 (Hz):Most LCD Monitors
 * 75 (Hz):Most CRT Monitors
 * 120 (Hz):Special gaming monitors - in WoW, these are meant for use with the Nvidia 3D goggles.

Changing this setting
In-game, type the following /console gxRefresh setting

Alternatively, you can exit wow, open the Config.wtf file, and add the following line: SET gxRefresh setting

Fix for current issue
When wow loads, it'll automatically reset gxRefresh back to 60Hz. However, to get around this you can edit your Config.wtf file to 75/120, save it, then set the file to read-only.

Please note that setting this file to read-only will keep wow from saving any engine, graphics or sound changes.