I figured. Foundation is limited to 8GB: [URL]#physical_memory_limits_windows_server_2008_r2 
Hi, my name is Juan Marrero.  I work for Bike Stop, Inc. in Puerto Rico. I recently upgraded the CPU and the RAM in our PowerEdge T110 Server.  Originally there were only 4GB of RAM.  Now it have 16GB installed but only 8GB are usable. The CPU was a Intel Xeon x3430 and was upgraded to an Intel Xeon x3470.  No issues here. The specifications of the memories are: 4GB DDR3 PC3-10600 ECC Unbuffered DIMM (4 of them) to a total of 16GB of RAM.  I searched the internet and found nothing in the BIOS to not limit to 8GB. Is there a limitation, no matter what the motherboard and CPU say they can handle?
Dell PowerEdge T110 not using all Ram installed