Hi @fromax , and many thanks to @Dufus and many others who contributed.
I have a Xeon e5 2683 v3 - 2GHz -2,3GHz ES model F stepping 1.
MSI x99a raider bios p50
I did as you say, i changed the strings, and when i load to check with UBU, I see that the 306f2 is deleted from bios, and i flash it...