Monitor causing lag in games

[lilythsgrim]

Hello,
I'm getting a lot of lag when gaming. I'm running a Gts250 4gb of ram dual channel and a AMD Athlon 2 x4 620 at 2.60 GHz I have Vista home premium 64bit My monitor is a Dell 18.5" Widescreen LCD Monitor 1366x768 w/ 5ms Response time I'm running the game "Star craft 2" on low and still getting lag if there is a lot of stuff on screen Where as my roommate is not and my comp is better then his except for his monitor. it is a Dell SE198WFP 19 inch 1440 x 900 Response time 5 ms

 

[tecmo34]

Are you both running at the same game resolution? Your roommate may be running at 800x600, which doesn't require as much horsepower, as running at 1366x768.