Aurora R8, BIOS option XMP is disabled and cannot be changed

You need to purchase memory with Extreme Memory Profiles (XMP) for that option to be enabled.  With Kingston for the R8, that would include the HyperX Fury.  This is different from the standard JEDEC profiles.  When you purchase RAM without XMP, then it will just run at the standard JEDEC timings pulled by your computer.

As an aside, I purchased my Aurora without the XMP option, and separately purchased the retail Kingston HyperX Fury from amazon, and I am able to select between the two XMP profiles in BIOS. 

This is the timing table from the module's SPD. Probably more correct to state that I wish the R8 BIOS would use the JEDEC standard profile of DDR4-3200AA when a DDR4 module supports it.

Yeah, unfortunately, Dell's BIOs only lets you select between applicable XMP profiles on this model.  Not sure if you might have any luck using third party software like Intel XTU (but do note that changing RAM timings my be blocked by Dell's BIOs). On the plus side, your are at 19 19 19 vs 22 22 22. 

Thanks for mentioning Intel XTU.  I had not heard of that.  I tried it and XMP settings could not be applied. Looks like as you said that the Dell BIOS does not allow the Intel tool to activate the valid XMP/JEDEC profiles that these Kingston DIMMs support.

Now, for a teachable moment.  I do this out of love, my fellow internaut. No sarcasm. 

CL=22 @ 3200 MT/s has lower latency than CL=19 @ 2666 MT/s.

Column Address Strobe (CAS) Latency (CL) is usually shown in units of clock cycles in DIMM specifications.  CL can be converted to units of seconds by multiplying by the clock period.    

For example, 

CL=19 clock cycles @ 2666 MT/s = 19 clocks * 1 second/1333333333 clocks = 14.25 ns

CL=22 clock cycles @ 3200 MT/s =  22 clocks * 1 second/1666666666 clocks =13.75 ns

Both of these DIMM examples have values that comply with the JEDEC specifications that help manufacturers of memory controllers (Intel, AMD, etc) and memory (Micron, Samsung, Hynxi, etc) make compatible products. 

https://en.wikipedia.org/wiki/DDR4_SDRAM

https://www.micron.com/-/media/client/global/documents/products/data-sheet/dram/ddr4/8gb_ddr4_sdram.pdf?rev=fc43fedde2ac411a819ed8ee3e6cbb68

@arobg :

Here's my observation:

The level of frustration with this locked AW ecosystem increases proportionally with one's knowledge about computers. 

Amen!