there is. 3D monitors often take a 60Hz input, split it into 30FPS per eye, then double them. so you really only get 30FPS per eye, and its craptastic. true 120Hz monitors (of which some or many are 3D capable as well) actually allow you to set a 120Hz refresh rate in windows. HDTV's are the worst offenders for 60Hz inputs, while they advertise higher.