I'd like to know if there is any way limit the framerate of games to half the refresh rate of the monitor. You will ask why do I want to do that... there are some reasons:
1.- If your rig is powerful enough to produce 60 fps with v-sync enabled, everything is ok. But if it's not... you'll have to disable v-sync, or suffer the rollercaster of your fps going up and down with your GPU trying to achieve the desired 60 fps. The problem when you disable v-sync, is that fps are not constant, and for a racing game for example, the feeling without v-sync can be worse with a fps between 35-45 fps than with 35 constant fps.
2.- I know there are programs to limit your fps to a certain number. For example Dxtory. This little program is great not only to limit your fps but also to record videos (even better than Fraps). But the problem with Dxtory, is that you can limit your fps, but there is no option (not to my knowlegde at least) to tell the GPU to exactly limit the fps to the half of the refresh rate. Here there is an example:
If your refresh rate is limited to 60 Hz, and you limit your fps to 30 with v-sync (to avoid tearing), your game with run at those 30 fps, BUT, there will be some frames out of the range, producing very annoying stutering
I think that if there was a way to limit the fps to exactly the half the refresh rate of the monitor, there would be a fantastic way to get a quite smooth game experience.
In addition to what neon said, some games have an in game setting that lets you limit the max fps to 30 or 60 (half a 60Hz and 120Hz monitor, respectively). In addition to this, some games have this option in the .ini file as well.
I know some games, such as Half life 2, and all the games that use Unreal Engine 3 (mass effect 1 to 3, bioshosk, Batman arkham asylum...) have this option. But for the rest, it's not that common. For that rest I use Dxtory. But as I said before, the problem is that I'd like to use v-sync and fix the framerate to the half of the refresh rate for a really smooth game experience. For instance, in my laptop I can't get 60 fps on Dirt 3. I plug my laptop to a CRT monitor, with 84 Hz mode. With Dxtory I cap the framerate to 42 fps, and the game experience is much better, but it's not truly half the refresh rate of the monitor so sometimes it stuters a lot...