I've been using this trick for over a half a decade now, and there have been multiple numbers mentioned and methods for achieving this goal. One thing I would like to get some feedback on, is this method that seems particularly tailored for Source engine games: http://steamcommunity.com/sharedfiles/filedetails/?id=129836524 It lists approximate times needed to be taken into account for the amount of time required for input polling in the engine at a given refresh/frame rate, and this being a useful calculation when capping fps with vsync on. For instance, it lists ~7ms as the necessary input polling time at 120 fps/hz, and ~19 ms at 60 fps/hz. it then recommends a specific framerate to cap the game to internally, or by rounding to the nearest whole number for external framerate cappers, as they were not able to be as granular as the more recent version/beta of RTSS, back when this guide was written. Any of you Gurus have some input on this, or think it is relevant/useful compared to just capping at .007 below refresh as is suggested here? Is what's suggested in this guide the best method for source games since more information is generally known about that engine given it's age/lineage, whereas we may not have as accurate information about the required input polling time for specific fps/hz rates in newer/different engines, thus making a general rule of .007 below refresh rate the best known option for other/newer engines? There is some very solid information in this thread for people interested in this method. I'm glad I stumbled upon it, and look forward to seeing the evolution of things like this, whether implemented directly in RTSS or into future game engines by developers. Thanks! EDIT: In the past, I've used this frame cap/vsync method along with ULMB on my monitor, to get maximum smoothness with minimum possible input lag in various games. Is this a good practice, or is there some reason I'm not aware of that this should not be used in conjunction with ULMB? In some games (like the indie game Ziggurat), it has been necessary to use methods like this to fix inherent stuttering in the engine when running at high refresh rates/fps.