XPS 8940, switch UEFI to Legacy Boot Mode

I tried to 

1) clone my wife hd from old system to the ssd via bootable dvd with Ghost.

2) if not possible, then I would like to a fresh installation with windows 10 pro.

The lack of toggling UEFI to Legacy is not a show stopper, but just wonder "why"

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Not from USB but from legacy windows 10 pro installation dvd

@hanklee2000  - What do you mean "boot from BIOS"?

If I understand correctly, you want to boot from a USB stick, correct?

Plug a bootable USB into PC while the power is off. Then power PC on and start tapping F12 when you see the Dell splash screen.

When the F12 menu opens, look for the option to boot from USB.

Similar approach to try to boot from CD. Put the bootable disk in the drive first, restart the PC and tap F12 when you see the splash screen.

Even if you clone the HDD from the old system onto the SSD in the new system, it may not boot because the hardware is likely to be very different between the old and new PCs.

Did you look on the F12 boot menu for option to boot from optical disk or USB?

Why would you need to do a fresh install of Win 10 Pro on a new system? It should already be installed on the SSD. But if Win 10 Home was installed by Dell, you'll need to buy an upgrade license from Microsoft to install Win 10 Pro.

And you can do the fresh install by going to the Microsoft site and following their instructions to create a bootable USB with Win 10 v20H2, but it will only allow you to install the same version that you have now, Home or Pro.

And for the record, BIOS on the XPS 8940 has this option:
Enable Boot Support
Enable or disable booting from USB mass storage devices such as external hard drive, optical drive, and USB drive.

Are all new pc sold by other companies no longer support legacy boot mode or... That is my question. 

If it just Dell, then I probably return it and get others before I go too far.. Or I have to live with this new rule and move on..

Find the answer: Intel: We're ending all legacy BIOS support by 2020

https://www.zdnet.com/article/intel-were-ending-all-legacy-bios-support-by-2020/#:~:text=Intel%20technical%20marketing%20engineer%20Brian,and%20datacenter%20platforms%20by%202020.&text=However%2C%20users%20won't%20be,CSM%20on%20Intel%2Dbased%20PCs.

For the question of replacing new pc os to win10 pro, because wife needs Remote Desktop function and we have win10 retail license not being used... So..

You should be able to boot from that DVD if you enable the setting in BIOS I mentioned above, and then boot to that disk via the F12 menu.

But, remote desktop can be made available in Win 10 Home.  It just requires some extra work...

Or, just create the bootable USB at the Microsoft site and when prompted, enter the product key from your Win 10 Pro license.

Is it possible to remove/disable/workaround UEFI. I've been buying Dells for years for home use. It's always been a matter of nuking Windows and installing Linux. With my XPS8940 things are not working. I've followed my standard procedure of setting AHCI mode, and doing the Linux install. I disabled secure UEFI and selected SATA0 as the boot drive, after marking the first linux partition as bootable.

The bootup message is that no bootable partition is found.  Somehow, it managed to find the bootable USB key when I was doing the Linux install, so that works. Looking at the partitions  with fdisk shows no Windows residue. Going into advanced mode gives a warning message about first partition not starting on a physical secor boundary!?!? If nothing else, is it possible to edit UEFI to pick up the first Linux partition an boot off of it?

@WDXman   You should have started a new thread...

fdisk doesn't read GPT-partitioned drives correctly and typically gives that error message. You may need to use parted or gparted to partition this drive and start over.

Lots of discussions about this error and Linux on the net so Google...

You are incorrect and make assumptions that do not fit modern Bios with Secure UEFI and TPM and other areas. I have the same issue as this equipment is being used with critical testing systems we create images and clones to minimize downtime. We have legacy equipment and test stands that this will work such as Win 7. But the newer systems need a lot more . Probably due to WIN 11 requirements. Please read back and hopefully you can come up with an answer because there doesn't seem to be one 

Sure but you have to turn of Secure boot which is not there on any of the three brand new machines You answer is incomplete so maybe i am missing something

@hanklee2000

@roblv 

@RoHe 

@WDXman 

All Vendors Dropped Legacy Boot Support Per microsoft specification for Class 3 bios.  All vendors are going along with this Not just a windows issue also applies to Linux older Distros.

Newer than 6th Gen Skylake No Legacy Support Dell KB 000125414

No more 32 bit and no more CSM.

This was not Dell it was INTEL and AMD and NVIDIA etc bowing to Microsoft Demands that after 6th gen no more legacy anything.

64 bit only WIN10 only period End.

Last machine to support Legacy is Optiplex 3040 7040 9040.

Brian_Richardson_Intel Removing Legacy Boot.