|Always use Vsync. It will keep the game flowing more constantly and prevent speed ups. |
On CRT monitors it was used to prevent screen splitting when for example in an FPS if you would turn around rapidly you might get two or three lines horizontally with slightly different images, or images not in sync. This was the graphics card rendering either too slowly, or too fast for the CRT's refresh rate and the split screens were frame rendered ahead or behind the current frame. Vsync kept this from happening..... as much.
PowerMac 9600(1 ghz G4)
ATi 9200 PCI