Booting Windows 10 from external USB SSD

Question

Hi, DELL OptiPlex 5050 with Windows 10 Pro. I have an SK Hynix ssd installed as my system drive (drive C) and I have this cloned to an external ssd (an ADATA) the caddy being connected to the PC via USB3.  The ADATA appears in File Explorer as drive E.  When I tap F12 to do a one time boot the ADATA drive is one of the options I am offered, I select this but on boot the PC invariably boots to the original SK Hynix. I have used Macrium and Casper to make clones and neither work.  I have previously used Casper to successfully clone when I had an internal second drive so I have no reason to suspect the actual cloning.  As the cloned drive is one of the options in the one time boot options I cannot see why it will not boot.  Any ideas would be welcomed, thank you.

fireberd · Answer

When you did the clone, did you clone the entire drive, all partitions?   One thought.

optijohn · Answer

firebird - yes, I cloned the entire drive, all partitions. Disk Management shows all partitions - EFI System partition, Primary partition and OEM partition on the cloned drive as healthy.

When I tap F12 to get the one-time-boot options the cloned drive is one of the two options but the OptiPlex always boots to the C drive.

Thanks for your input.

speedstep · Answer

Windows is not MAC OS. You cannot primary boot from USB and clone to internal drive OR vice versa.

Booting USB SSD is specific to particular models AND must be a WINDOWS TO GO installation then F12 booted while in LEGACY MODE SECURE BOOT OFF CSM ON.

Newer Models with CLASS 3 UEFI do not allow CSM or Legacy Booting.

The other trick being used is a MACBOOK PRO to download the ISO.

So RUFUS with WIN10 ISO and SANDISK USB SSD and ISO file from Macbook Pro it works.

I have all the hardware in the video and have tried this with the SANDISK and it definitely works.

https://www.youtube.com/watch?v=VpZJpzPvqtk

Optiplex Desktops

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