On ne voit pas l'option USB dans tes captures d'écran.
C'est une nouvelle installation matériel ?
D'apres le site Asrock :
Question: Does ASRock motherboard support "Boot from USB device", if my USB device is bootable?(4/15/2003)
Answer:
Yes! All of ASRock motherboards support "Boot from USB device".
When the system boot up, please press "F8" or "F11" to enter "Boot Menu" and select USB device for your fist boot device , then the system will boot from the USB device which you selected. For P4I45D, please plug the bootable USB device to USB port 2,3.