M17X, how would a single ATi HD5870 graphics card perform ?

Hey 5150Joker I have a couple of questions. I have had problems with my old M17r1. After 10 months!!! I got a replacement. The m17x r2 that I have now has the 920xm, dual 5870, 8 gb 1333 ram, rgb led, intel 6300, and 256 gb ssd. Now the new machine works great except for dirt 2, which you mentioned worked flawlessly for you. I have the micro-stuttering or what I think that is. For me it is the little snag when playing, like the frames just stop for a split second and the game lags. This is particularly annoying for racing games as it messes you up dramatically when turning. But I also have this problem for GRID which is also a codemasters game. Both stutter. At least this system does not have the fps dropout right? thank god. All other games work fine except for Dirt 2 and GRID. Can you giver specifics for your drivers and your system specifications, or can you see a problem with my system? I know there is no "specific" crossfire support for them but they should work right. Not even if I take the crossfire off, does the game work.
Any ideas? Drivers? Something? I really don't want to return this system as it works pretty amazingly except for this little problem.

Any suggestions would be great. Thanks