I’m just doing a pair of r740xd right now. Flip it all over to UEFI boot. Boss controller is in the BIOS F2 settings while powering up. I’m assuming you also have a PERC 3xx or 7xx series raid card. That is from lifecycle controller under storage. There is a tiny text link that will let you create the first array. Disk selection and accept configuration can be reached by scrolling down off the screen - stupid layout. None of it will take until you hit the accept now button.

If you can wander around to the controller settings goose the BGI parameter to 80% or so as my 8x4TB SAS array took the better part of 12 hours to initialize at 50%.