Depends on what type of monitor you use.
I just picked this of the internetz, its the basics.
Most games disable it by default, some recommend disabling in the gpu driver settings.
The key word is tearing, not to be confused with lagging.
LCD monitors are set at 60mhz, so in theory you should be capped at 60 fps but as we all know "life ain't what it seems to be" (thats me that wrote).
Vsync matches your monitors refresh rate/frequency, with a 3D applications frame rate.
In other words, It doesn't let your frame rate go above your monitors refresh rate. 85 Hz. = 85 FPS
100 Hz. = 100 FPS
and so on. (That was iternet that wrote).
Disable in the Nvidia control panel and in the in-game options and report back.
Vsync will bring your fps to a lower rate depending on the application fluency but at the same time will give a smoother less jittery image...I think
@ Murphy: Its not only RO as you know already, it seems more prominent in XP than Vista but that is also open to debate, I am waiting for final SP1(vista) & SP3 for XP. It seems that things are looking optomistic at the very least.
On a personnel note , all this bullocks is holding me back from upgrading my computer (at the same time that of my boys, "come on Dad give us your vid, I wanna play Assassins Creed"
as it should be played).
Danzig is special I tell thee, I know I was there.
Thanks...