Greetings.  I am curious if anyone else is using GSkill F4-3733C17D-32GTZKK with the Z370 FTW memory.  No luck with XMP Profile but if I go manual and set the voltage somewhere between 1.40-1.45 on memory it seems stable.   Memory is stable @ 3600 on XMP voltage but not at the 3733 speed it should be.  
 
Curious if others have had problems and if they came to the same solution I am at/testing.

Problem appears to be resolved.
 
I noticed that my 'ring ratio' was matching my overclock (4.9ghz) x49 being set 'Auto' in the bios.  I did some quick reading on what 'ring ratio' is and then changed the setting from 'Auto' to '46' in the bios.  I was able to lower my vcore voltage a good bit and maintain stability.
 
On the next reboot I lowered the memory voltage from 1.45v to the XMP profile value of 1.35v.   I failed to mention this before but I am using XMP values but manually setting them.  I will run a long stress test tonight -- but it appears to be very stable so far.  I went with 2x16gb sticks of 3733 in hopes of pushing them to 4000 instead of using 4x8gb.  

Reporting back -- Still no issues so I'm calling it fixed.