Booted a Dell OptiPlex 7090 Micro from Windows 10 and 11 ISOs via an iodd Mini PRO without issue. Changed SATA Operation from RAID / Intel RST to AHCI* to expose the internal NVMe SSD; external boot still worked. Copied data off the internal drive, then wiped it with diskpart's clean command. Post-wipe, external boot attempts failed: selecting the device in the Dell boot menu and pressing a key at the "Press any key to boot from CD or DVD..." prompt led to a Dell SupportAssist "No bootable devices found" screen, with just a Continue button which rebooted the machine. Fix: Disabling Secure Boot restored external booting. After installing Windows, re-enabled Secure Boot without issue. Likely cause: Appears to be a Dell firmware bug rather than genuine signature rejection, since the firmware successfully ran the external media's first-stage loader (which displays the "Press any key" prompt) yet with Secure Boot enabled apparently failed the hand-off to the second-stage Windows Boot…
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