What specific processor are you using .. processor number or CPU speed or other data would help.
the lower priced Xeon 5500's will only run up to a certain memory speed (see below). If you have use memory that is capable of running faster it will only run a the the max speed indicated below.
the Xeon E5502, E5504, E5506 will run a max memory speed of 800MHz
the Xeon E5520, E5530, E5540 will run a max memory speed of 1066MHz
the Xeon X5550, X5560, X5560 will run a max memory speed of 1333MHz.
Here is of DDR3 memory population guidelines for the HP DL380G6 and for HP DL360 G6 (this information is in the HP Product Bulletin). Even if i wil use the Xeon X5550, X5560, X5560 and install all memory dimms in all slots, dimms speed will be 800Mhz. A similar situation on IBM's servers (x3650 M2, x3550 M2). This is vendors limitations or so works memory controller in the Xeon 5500?DIMM Type ->Registered Dimms (RDIMMs)Unbuffered with ECC DIMMs (UDIMMs)DIMM Rank ->Dual Rank (2R)Quad Rank (4R)Single Rank (1R)Dual Rank (2R)DIMM Capacity ->2GB4GB8GB2GB4GB8GB1GB2GB1GB2GBDIMM Native Speed (MHz) ->133313331067*1067*1333**1333SLOTS THAT CAN BE POPULATED18 slot servers181818*12*12**12MAXIMUM CAPACITY (GB)18 slot servers36<td align="center" class="bodycopy" valign="middle...
You are right .. i forgot about that dependency when i wrote my previous response on why your memory may be running at a slower speed. the memory speed is also dependent on the number of DIMMs you populate per channel.
one DIMM per channel (up to 6 DIMMs / server) .. can run 800, 1066 or 1333MHz memory
two DIMMs per channel (up to 12 DIMMs / server) .. can run 800 or 1066MHz memory
three DIMMs per channel (up to 18 DIMMs / server) .. can run 800MHz memory only
the Xeon E5502, E5504, E5506 will run 800MHz memory speed only
the Xeon E5520, E5530, E5540 will run 800MHz or 1066MHz memory speed
the Xeon X5550, X5560, X5560 will run 800MHz, 1066MHz or 1333MHz memory speed.
One other dependency I should note while we are on this topic. If memory reliability features like mirroring or lockstep operation only function if you have 2 channels of memory populated (can't do odd numbers of channels here)
This is a complex topics and we had many questions like yours as we enabled this product across the industry. Hope this helps ... I have provided a simple visual cheat sheet that i refer to on this topic