A littel update about my setup. The node is running fine.
I was a bit upset over the unused ssd space, and would not set up an 3. node (yet) so i bought primocache.
changed the volumes to 2 ntfs parts, one 500GB big. and converted it with primocache to L2 buffer partition. and after that i reenabled 3% overprovisioning (to mock arrogantrabbit 
)
I set the read-only buffer mode and…
… then i realised for write caching wich goes ALWAS PARTLY over RAM in primocache !!! i need an UPS(USV) officialy. (Vadim does it without protection 
)
So ibought an UPS( @arrogantrabbit yes you were right in the late run over that)
Cheapest Blue walker fits even in the narrow space
and some more RAM despite not realy neccesary.
and forgot the mobo compatibility, so its ddr4 2400 instead of 3200 but did not notice a negative difference. 47 of 64GB are now in use.
(i will never financially recover from this 
maybe in 20 months more life of my first node)
So now i can go full full metal cache it. with different cache paths for read-over-nvme and write-over-RAM.
Even my system disk is now included. It indeed speeds up the gaming loading times.
also for the databases (again arrogantrabit was right in the end, despite i would not have him that)