I definitely don’t see the option for entering bios via F2.   Anyways, the solution ended up being pressing control C during boot up, which let me change the boot order of the two cards.  
I have a Dell R720XD with two raid cards in it. One is a PCI H710, the other is the H710 mini the system came with. Both cards are flashed to IT mode. The mini is connected to the 24 drives up front, the PCI card is connected to the drives in back (OS is on rear drives). On boot, the system recognizes 2 controllers, and all drives attached to each of them.  However, when I go into the Bios to select the drive to boot off of, I cannot select the correct drive (it only gives one chose).  Doing some testing, if I remove the front backplane drives, the system will correctly select the rear drives and boot from them.  I can manually get the system to boot using this method and putting the drives back in after boot up, but this obviously isn’t a great solution.  For some background, the PCI H710 is being used to pass through the boot disks to Proxmox, and the H710 mini is passed through to a TrueNAS VM to give direct access to the drives. 
Cannot choose correct drive to boot from