My XPS 8950 Memory Seems Slow

I recently installed the CPU-Z utility to check on the speed of my XPS 8950.  It seems to report that the RAM memory is operating more slowly than specified, but I may not be interpreting the results properly.  Any help would be appreciated.

My machine came with two 8GB memory sticks in the default slots (2 and 4, which are labelled DIMM1 and DIMM2, respectively) on the motherboard.  These are supposed to be DDR5 4400MHz memory, and the BIOS shows that speed.  The Setup and Specifications document says this configuration should run at 4800Mhz (or maybe it means that is the maximum speed if the memory is capable).  The CPU-Z program reports the DRAM Frequency is 2195.2MHz as you can see in the following screen shot:

That seems to be half the specified speed.  Why is that?

The CPU-Z website has an FAQ which seems related to this.  It says:

Why does CPU-Z misreport my memory module specification? For example, my DDR2-800 is reported as DDR2-667.

The memory theorical bandwidth is computed using the module access time information for the maximal CAS# latency value, included in the SPD area. If the computed bandwidth is lower than the one specified on the memory module, that means that the SPD information on the module is not correctly programmed, or most likely that the bandwidth is not given at the default memory voltage, but at a voltage defined in an extended profile (EPP or XMP).

This goes beyond my technical understanding, so I’m showing a screen shot of the SPD tab:

What does this mean?