Got the 1900X just because I don't need to spend more until the 7nm models pop up.
Using XSPC block, quick overclock to 4.0Ghz/1.35v - 3200xmp ram.
Idles at 26ºC,"normal" load temps are 50ºC, +1hr prime95 smallFFT goes up to 64ºC (VRMs go up to 49ºC with a 80mm fan). Water idle vs prime load delta is like 2-3ºC.
Had serious doubts about the block when I installed it but it seems I don't have to remount.
Will go for 4.2 and tune the volts when I have time.