This is the classic limitation of the MIH61R motherboard. While the OptiPlex 3010 version of the MIH61R officially supports 2nd and 3rd generation CPUs, the OptiPlex 390 version does not, even after a BIOS update. The hardware is identical, but the BIOS has intentionally different capabilities. If you need to use a 3rd-gen CPU, you would need the BIOS from a 3010 and an 8MB BIOS chip, as the 390 uses a 4MB chip and different programming.
4.3 UEFI capsule or BIOS Setup method
If the screen remains black, you may need to clear the CMOS by removing the coin-cell battery for 5 minutes, then re-inserting it. dell mih61r mb 100971 bios upd
Compare image against vendor-supplied images and known-good hashes. This is the classic limitation of the MIH61R motherboard
Keywords used: dell mih61r mb 100971 bios upd, Dell Optiplex 3010 BIOS, MIH61R update, 100971 motherboard flash, H61 BIOS recovery. If you need to use a 3rd-gen CPU,
4.5 Automated enterprise deployment