Thanks for all your responses…
All the software I've tried to mine freezes when started the two cards.
Seems the Motherboard has gen 1 Pci-e 16x slots. You will need at least gen 2.0
Really? These are the specifications: 3 x PCIe x16 slot, support NVIDIA® SLI™ technology, at x8, x8,x16 or x16, x1, x16 speed
Maybe shall I switch to Linux? It would be easier?