I am having a very annoying problem with my GTS 250. Usually, when I'm playing a game that requires some good GPU power, I can hear the GPU fan quite loud, which let's me confirm that it is running at 100% when playing a game. This isn't happening on the new MOH:W. Every time I am playing the game, I can barely hear the gpu fan. At start the game runs fine (when the fun is starting to speed up) but then it sort of stays low on fan speed and the game starts to lag and/or has performance drops quite usually.
This is a an odd problem to describe, I hope I've made my point.
I've been playing MOH: Warfighter a little bit on my new rig but my old system with a Quadcore and 5870 got those lag spikes randomly as well. I'm not sure what I did to fix it, but that game is really buggy to be honest and you might want to compare your hardware to the recommended specs of the game.