So i own a few games that give me this issue, Call of duty: Modern warfare 2, Left 4 dead 2, and something else. I was playing Jedi acadmey the other day and wondering, what can i do to make this game look any better. So i go to the video options and set everything to max (Theres an overall detail bar) and click apply.
When it goes back to game ive got that input lag in this game as well. Vertical sync is what does it. I disabled it in Jedi academy and it was gone, and i did it in all the other games as well.

Gone, so i did more reading on the subject. It has to do with how many frames are being sent to your monitor and the monitor recieving 1 too many so frames display late. The best alternative if your getting artifacts or fragmented corners is to enable triple buffering but not full blown vsync. Other wise deal with it because i know i cant hit ANYTHING with v-sync on. THIS IS NOT A HARDWARE ISSUE. If its anything it has to do with your monitor being under a certain amount of hz. Mine is 60hz, and im running a DVI - HDMI cable. Lots of things can probably factor into this but i havent read any further on it. If you find any more please post!