Search results for ‘P5E3’ - Win-Raid Forum (level1techs.com)
EDIT: You may not find a bios ready to flash but there is similar users with same board and guidance to do it yourself, besides the regular guides, choice is yours wait for it or start working on it:
[Experimental] NVMe Option ROM - BIOS/UEFI Modding / BIOS modules (PCI ROM, EFI and others) - Win-Raid Forum (level1techs.com)
Using this method you will not find a bios mod ready to flash as it depends on the NVMe disk/controller of each user, so its an edited Oprom with a specific HW ID.
Thas why you cant find one ready.
These are not modern UEFI bioses for regular NVMe DXE module insertion.