I just got an i7 920 CPU, with an EVGA 3X SLI board and 6 GB of DDR3 RAM. My old system was a E8400(stock settings) with 2 GB of RAM, and it played COD maxed out just fine w/o a stutter. So I'm playing for a min, then about every few feet a run, there is a quick 1 sec stutter and I hear my fan die down. I have an ATI 4870 with updated drivers, and my friends think it is some driver conflict or something. I mean, it can't be to hard on my system, it's way better than my old, and my old played this maxed out fine. Anyone know what's making this stutter? This is the only game it stutters on. Plays Crysis just fine and GTA 4 just fine as well.
There can be several things at play here. First things first, download CPU-Z and GPU-Z, run them and make sure that your clocks are set right. Second, uninstall your graphics drivers completely, reboot, and reinstall just to be safe.
If this doesn't fix the issue I have another idea. Its possible that your CPU has C1E enabled or whatever the throttling is called. This will downclock your CPU when its not being taxed. Its possible that for some reason CoD isn't triggering the full speed and its lagging because the proc is running slow (However, i rather doubt this).
One other thing to check is chipset drivers, mainly the audio drivers. Audio drivers for some reason get corrupted more often than others, uninstall/reinstall just to be safe.
Your board is SLI, make sure that your card is in the main slot since you are only using 1 card (and with ATI can only use 1 on this board).