I hate to disagree with you, but whether the memory is XMP or not makes no difference. If the memory is rated at 1600 MHz and he has configured the BIOS settings to make the memory operate at 1600 MHz (which is 800 MHz per slot for Dual Channel memory), then the memory should be operating at 1600 MHz. I would suggest that he use CPU-Z to determine if the memory is running at the correct speed.
BTW, after upgrading the BIOS to KGIBX10J.86A.4752.2010.0217.1029, 2/17/2010 and power cycled my machines, the memory frequency readout is wrong in the the Intel Desktop Utilities ver 3.0.16.082 and CPU-Z 1.53.1. My memory is G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBRL and I have them set up to run at 1600 MHz, but in these software packages, the memory is showing up ar 1333 MHz.. The BIOS is showing that they are running at 1600 MHz.
So there may be a small bug in the BIOS.