Finali found time to migrate from my old workstation (Dell r730XD 24 SFF, 4x U. 2 NVME) to bit newer Dell r7920 (Yes, rack, not tower).
Why?
1: 25gbit NIC.
2: much more airflow.
3: NVME boot.
What I did:
Remove the front 3.5 caddys and backplane, remove corresponding wires from onboard SATA controller .
Cut and file air shroud to fit GPU.
Cut and file CPU heatsink to fit GPU.
Power GPU from 2 sources: rizer 1 power and riser2 power.
Install OS on Intel P4800x SSD. (Yes, Finally, Optane as an OS boot device).
Install 1100W power supply, because it comes with 1600W PS but on a regular 120 receptacle it gives only 800W.
Enjoy!
Next steps: setup direct link to NAS (25 gbit, RDMA, ISCI).
Figure out pci ex bifurcation. System can see only one of U. 2 ssd connected thru 16xPCI to 4 U. 2 SSD adapter.