Would you rather communicate in English? Ou en français? Mais mon français n'est pas très spécial
No, your French is perfect , but we can speak in English.
I have something new, I don't know if it's because I used this ROM (Z77MXD3H_HighSierra_L1c.F7e.rom), but now I can choose my disk by pressing the F12 key "Please select boot device", before my disk containing High Sierra never appeared