DDR3 10600 memory running at 533mhz

I bought a second-hand HP ProLiant DL160 G6 a year ago with 48GB configured in it. I discovered checking with cpu-z and doublechecked with speccy the memory runs at only 533Mhz. I checked the configuration with the HP memory configurator and the banks are populated correctly for max performance. There are 12 banks populated with micron and hynix memory of 4gb, all capable of running 1333mhz. What could me wrong here?

 C:\Users\Administrator>wmic Memorychip get manufacturer, partnumber, speed, seri
alnumber, devicelocator, banklabel
BankLabel  DeviceLocator   Manufacturer  PartNumber         SerialNumber  Speed

BANK0      PROC 1 DIMM 3A  Micron        36JSZF51272PZ1G4F  C5DF65D7      1333

BANK1      PROC 1 DIMM 2D  Micron        36JSZF51272PY1G4D  951565E0      1333

BANK3      PROC 1 DIMM 6B  Micron        36JSZF51272PZ1G4F  3F3160D6      1333

BANK4      PROC 1 DIMM 5E  Hyundai       HMT151R7BFR4C-H9   E28A3014      1333

BANK6      PROC 1 DIMM 9C  Micron        36JSZF51272PZ1G4F  26DF7E1A      1333

BANK7      PROC 1 DIMM 8F  Micron        36JSZF51272PZ1G4G  77FC67D7      1333

BANK9      PROC 2 DIMM 3A  Hyundai       HMT151R7BFR4C-H9   FB763433      1333

BANK10     PROC 2 DIMM 2D  Hyundai       HMT151R7BFR4C-H9   E18AA014      1333

BANK12     PROC 2 DIMM 6B  Hyundai       HMT151R7BFR4C-H9   DF8A1014      1333

BANK13     PROC 2 DIMM 5E  Hyundai       HMT151R7BFR4C-H9   6968511A      1333

BANK15     PROC 2 DIMM 9C  Hyundai       HMT151R7BFR4C-H9   F28A7014      1333

BANK16     PROC 2 DIMM 8F  Micron        36JSZF51272PZ1G4G  76FC67D7      1333

533MHz is not possible on this gear. This is a problem with the interpretation of the CPU-Z results. Multiply that frequency by the data rate (2x or DDR), giving you 1066MHz.

But 1066MHz isn't what you were expecting either!!

For the rest of the setup, there are a few factors to consider. The DIMM population guidelines for the server are below. You have 18 DIMM slots, and TWO DIMMs per channel are populated. That should give you 1333MHz, assuming all DIMMs are registered RAM (not UDIMMs). Please try a firmware update on server and also change the BIOS setting that allows you to run two DIMMs/channel at 1333MHz. It should be labeled "Two DIMMs per Channel at 1333".

After all of this, CPU-Z will show 666.5MHz :)