Many video cards provide polarity options for each scan mode. Why?
Probably to be compatible with older monitors. Most modern monitors are auto polarity detecting so the settings should not matter. (Note that some of the digital PC video standard did have specific sync polarity specifications.) Some software programs that directly access the video card may even be changing sync polarity – for apparently no reason – without you being aware of it. Your video card determines the maximum video rate you can generate. The monitor has to be able to lock to it. So, if you cannot setup higher than some specified rate (i.e., the options do not exist in your menu), it is a function of the video card and drivers. If you can set it but the monitor displays garbage or nothing at all, it is a limitation of the monitor. The sync polarity rarely makes any difference and if it does, the effects will be obvious – picture shifted left/right/up/down on screen – or just won’t sync at all. If you experience problems of this type, experimenting with the sync polarity may be
