As it has been indicated by Peter Wertz and Dr. Strangelove at:
The amount of memory that you see reported would be expected.
I have to acknowledge that we may need to test on that XMP issue you are reporting, so please, provide the following information to move further on this:
* Board Altered Assembly Number (AA#):
* Board Serial Number (SN#):
* BIOS version:
* Processor model:
* Memory part number and manufacturer:
* Power Supply model and wattage:
* PCI Express* card manufacturer and model:
Please use the Intel® System Identification Utility using the following site:
http://www.intel.com/support/siu_la.htm?wapkw=%28siu%29
That will generate an 8 digits code called Report Reference ID. Please let us have that code, this will provide us information on what is being detected on your system.