Just installed my GTX 680 and went to play Crysis 1.  I noticed that my fps never went over 24.  Checked on the web and it seems this was (is?) a problem. 
 
Edit: Also, when I go into window mode, my fps jumps by about 20 or 30.
 
Is there a definitive fix for this?   I read some ppl had luck with going to window mode and then going right back to full screen.....some had luck with creating their own resolution, but I was wondering (since most of these threads were back when the GTX 285 was new) if there was a real fix now. 
 
I'm using the lastest non beta drivers and here are my specs:
 
i5 760 @ 2.8Ghz
12GB 1333
GTX 680 SC

I'm playing on a 32inch LCD HDTV.
 
It seems everyone who has this problem is on a HDTV.

D Apocalypse

Make sure under the nvidia control panel under resolution that your refresh rate is not set to 24Hz.

That doesn't make sense.  I don't mean to "not listen" to someone who is trying to help, but no one plays at the refresh rate.....I tried and it's so bad.
 
In the end, I shouldn't have to put my refresh rate at 24. 
 
I disabled vsync and my fps skyrocketed and was unlocked. 

My fault.  I thought you said make sure it was at 24.
 
Either way I don't think it is.  I looked up the resolution and it's @ 60Hz.
 
I made a custom resolution for the same thinking it being a custom it would trigger something.  When I did that a new resolution appeared in the list of defaults and one was 24hz.
 
Not sure whats going on.  Though it seems to only be the Crysis games.

you may need to play Crysis in direct x 9. Either right-click the shortcut (automatically created after your installation) under the games submenu  and select 'play dx9' or create a shortcut out of the game executable in the root directory and add  -dx9 to the target in the properties sheet of the shortcut. i.e.: ...\Bin32\Crysis.exe -dx9

Did you check the games setting folder?

Hey, I resolved this issue for Crysis and Crysis 2 by going to the NVCP (Nvidia Control Panel) and making a custom resolution (1919x1080 for example) and setting that as the current resolution. Then you can revert to the 1920x1080 resolution you normally operate on. Then when you start either game, just go to the settings and change the in-game resolution to the custom resolution you made (it should be listed under the available resolutions). This should force the game to display at 60Hz and you lose very minimal screen space.
 
I had this issue when I played on my HDTV, was an issue solely the culprit of HDMI. Apparently the game engine doesn't like the HDMI signal, thus causing the issue.
 
Hope this helps

Sorry to dig this up but it pertains to what i just found, and also a much easier and better fix than the above. All you need to do in any dx10 game that has this problem, is go into the NVCP, go to in this case crysis (or any game having the issue) and change preferred refresh rate to "highest available". I just was trying to replay Crysis 1 on my 2x titan x's (lol) when it was stuck at 24 fps unless windowed. I remembered what i did to fix company of heroes 1 in dx10 mode, which had the same issue years ago, which was the preferred refresh, and low and behold, perfectly fixes Crysis without screwing with the res.

OV3RCLK4
I dont see that option in NVCP to change preferred refresh rate to "highest available". Can you tell me exactly where you found that setting?

Under global settings it should be listed right under power management mode.

LMAO... I'm sure someone above pointed it out but...
 
If you're playing on your TV make sure your TV supports higher frame rates. Note that even the larger manufacturers claim 120hz or 240hz and THEY"RE NOT! They interpolate and use other technologies to supposedly give a high refresh rate; and its all BS.