External boot no longer working after wiping internal drive

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 Manager; other Dell users have reported similar behavior.

Footnote

^* Otherwise download Intel Rapid Storage Technology (Intel RST) Driver version 18.7.6.1010.3 (SHA256: A2B2E20D6D8100E9EE344746F80849524C64490B90686A13C09268CADB976B37) and extract the driver files via SetupRST.exe -extractdrivers SetupRST_extracted. When "Select location to install Windows 11" appears, click Load Driver and browse to SetupRST_extracted\production\Windows10-x64\15063\Drivers\VMD\, which contains the Intel VMD controller driver (iaStorVD.sys) needed for Windows to detect drives behind Intel RST. Here is the full extracted directory structure for reference:

SetupRST_extracted\production\Windows10-x64\15063\Drivers\

AHCI\
  iaAHCIC.cat
  iaAHCIC.inf
  iaStorAC.sys
  RstMwEventLogMsg.dll
  RstMwService.exe
HsaComponent\
  iaStorHsaComponent.cat
  iaStorHsaComponent.inf
HsaExtension\
  iaStorHsa_Ext.cat
  iaStorHsa_Ext.inf
PinningComponent\
  iaStorAfsServiceApi.dll
  iaStorPinningComponent.cat
  iaStorPinningComponent.inf
  OptaneShellExt.dll
  PinningServiceApi.dll
  SharpShell.dll
  SharpShellLicense.txt
RAID\
  HfcDisableService.exe
  iaStorAC.cat
  iaStorAC.inf
  iaStorAC.sys
  iaStorAfs.sys
  iaStorAfsNative.exe
  iaStorAfsService.exe
  Optane.dll
  OptaneEventLogMsg.dll
  RstMwEventLogMsg.dll
  RstMwService.exe
VMD\    
  iaStorAfs.sys
  iaStorAfsNative.exe
  iaStorAfsService.exe
  iaStorVD.cat
  iaStorVD.inf
  iaStorVD.sys
  Optane.dll
  OptaneEventLogMsg.dll
  RstMwEventLogMsg.dll
  RstMwService.exe

❧ 2026-06-07