Warning message when trying to disable Secure Boot on Dell 3280 AIO

I've disable secure boot on numerous systems without incident?


You might, for safety reasons create a Macrium (or other product image)


I would also look through your BIOS for a "Fast Boot" (name maybe slightly different) and disable that. Then try booting.


When you created USB with Rufus was is formatted Fat32? Has to be for UEFI to see as I recall.

I do the bootable Linux USB drive differently. I download the LiveDVD .iso file [usually Mint] and save it to the HDD or a second Thumb drive, use it to burn the LiveDVD [exact copy of the original], boot to that disc then use the Disc Imager/Disc Writer applet to create the Thumb drive and pointing to that download as the Source. But having a running Linux helps shorten the process.

So that screen shot really looks like you want Legacy boot or at least CSM enabled. Do you have a setting for CSM support in BIOS?

I have since backed up my system with Paragon HDD Manager, and AOMEI Backupper Pro. I did it both by booting from the respective WinPe Recovery pen drives. (UEFI - Secureboot on )

As das10 said I would believe that disabling Secure boot ( ignoring the warning message), choosing [Legacy] in the Boot List Option, enabling "Legacy Option ROMs" and Enabling "Attempt Legacy Boot" ( all under the "BOOT" tab in the third screenshot in my first post) should put me in the legacy boot mode (UEFI - CSM) . There is no seperate setting for CSM support in BIOS. If there was one so explicit, I wouldn't have posted this thread . That warning message was so scary that I wanted to take an opinion here.

i have gone through the System Setup manual - where nothing is mentioned about the BIOS - and the Service manual where only the default settings are mentioned but nothing about CSM mode.

Now that I have the verified double backups, I shall go ahead and do it tomorrow and post whether that enabled me boot the Lucid Puppy pen drive.. For now I shall listen to some music and hit the sack.

I have not been successful in booting the Lucid Puppy pendrive on my system. I first tried disabling "Secure Boot , ënabling "Legacy Options ROMs" but keeping 'Boot List Option " as default [UEFI]"



I did get the option to boot from "ÜSB Storage Device" on F!2 boot options




Lucid Puppy started loading but in the process it complained ""Searching for files in computer disk drives...
[] Lupu-501.sfs not found. Dropping out to initial-ramdisk console... []
/bin/sh: can't access tty;
job control turned off
# _" and stopped.

Then I tried changing the Boot List Option to [Legacy] instead of [UEFI] and tried to boot Lucid Puppy. Lucid Puppy stopped with the the same error.

To make sure that it is not the pendrive or the ISO , I pulled out my laptop, updated Win7 and Win8.1 in it ( It was last updated in Dec 2019 when my Win7 Desktop died and this updating took hell of a time) and tried to boot Lucid Puppy in Windows 7. I was closely watching as it loaded and it clearly said Lupu-501.sfs has been successfully loaded into the RamDrive. It booted into Lucid Puppy successfully.




OK, my Windows 10 system is driven by Intel Optane memory coupled with the 1TB HDD. That 13 GB Intel Optane non-volatile memory acts as an accelerator caching the most often used data thus speeding up the boot process as well as program loading. It operates in Raid mode (and not AHCI) and can be enabled/disabled in Windows 10. It can also be enabled and disabled in the Device Configuration in the F12 menu but I am wary of doing it without a clear documented procedure.

May be I have to try it with another Win10 machine without Optane memory.

Agree with trying other machine.

I don't have any devices with Optane cache solutions