XEROWhitebelt

ok, so it could be completley out of the "amazing pc's now" but i brought the dell xps720..... i can run any game in full graphics, farcry,crysis, fallout etc etc, but why when i try and run ET do i only get 80fps or so and even then it will try forcing it'self further, so i capped the fps @ 125, never seems to hit it, yet on something like CS Source im running @ over 300......