Ok so a quick question, for Intel z370 boards is a lower cas or higher MHz better?
Currently running xmp on the 8pac ram with an 8600k on Asus rog z370 f
Hard to give a straight answer, depends on the board. My board prefers lower clock speed and tighter timings (i posted my findings in a separate thread)
On a OC Formula or Asus Apex then you can have your cake and eat it.
On lesser boards (mine included) probably best to start to start with 3200-12-12-12-28-1T and take it in steps to see how far the ram goes. Increase CAS timings +1 if no boot from that starting position. Once you hit a mhz blocker, increase the vdimm volts up to a max of 1.5v.
Then do a 17-17-17-28-2T test and focus on Mhz, take the two results and work out from there a nice balance for your system. The holy grail on air is 4000-12-12-12-28-1T with two sticks and lowest volts. If you can get to 3600-12-12-12-28-2T on air with 1.5v you are doing well.
I would avoid copying some of the testing you see on the web as they (usually) are binning single sticks and/or working with nice cooling setups.