I have recently build my rig, the specs are the below:
CPU: Intel Core i7-3770K (OCed at 4.3)
CPU Cooler: Cooler Master Hyper 212 EVO
Motherboard: Asrock Z77 Extreme4
VGA: MSI NVIDIA GeForce GTX 680 (Lightning Edition)
HD WD Caviar Black 1 TB 7200 RPM 64 MB
SS Corsair Force GT 240 GB
RAM: Corsair Vengeance 16GB (2x8GB) DDR3 1600 MHz (PC3 12800)
PSU: Corsair Enthusiast Series TX 850 Watt ATX/EPS Modular 80 PLUS Bronze
Monitor: Samsung S23A950D, 1920x1080, 23", 120hz, 3D, 2ms
I think this can be pretty much considered as a high end rig but meh, I am having fps drops all the time on BF3. Yesterday it even reached 28 for 1 sec during an explosion. Most of the times it is between 60~110 (everything maxed out).
Drivers are all up-to-date and I've checked the CPU usage during the game and I can confirm that it is not being fully utilized. The GPU (not overclocked) is also fine, the core clock speed during the game started on 1110MHz (which is the normal) and increased during time.
What do you think the problem is ?