Most likely you dont have anything attached to sats ports a&b and they should be disabled in the bios. Not sure about the DHCp messages
Our Dell PowerEdge 1900 has a new motherboard and now has a boot issue. I receive a SATA Port A & B Device Not Found error message. When I go into setup it too shows then as "Not Found."  The display on the front of the computer says PXE-E51: No DHCP or proxy DHCP offers were received.  Also, I replaced the Dell SAS Raid Controller card. Is this an issue anyone else has faced?
Poweredge 1900 New Motherboard Issue