Windows 10: Windows boot manager and hard drive disappeared after switching from Legacy to UEFI Bios

I have an issue when I change the Dell bios from Legacy to UEFI.I want to rebuild the system using DISM as we are doing mass deployments using network PXE boot.When I set Bios to UEFI boot manager does not show up and when I tried to add it, I get an error that the file system does not exist.So, I am not able to add the Windows Boot Manager.The hard drive also does not appear in the list which I assume is because it is windows 7 and not using GPT.After the image is applied and the system is rebooted it does not boot from the hard drive even though it has Win 11 install and it also has the UEFI

:)

 

I can't switch from UEFI BIOS boot to Legacy.

If you switch from BIOS UEFI to BIOS Legacy you will want to have a drive with MBR partitioning.

If you switch from BIOS Legacy to BIOS UEFI you will want to have a drive with GPT partitioning.

There are exceptions but the above are the general rules.

The ideal time to switch from UEFI to Legacy or Legacy to UEFI is during a clean install.

If you have files backed up then you can easily switch from one to other by modifying the BIOS settings.

The BIOS settings during a clean install will create the applicable drive partition architecture.

 

I can't switch from UEFI BIOS boot to Legacy.

Hi Albert. I'm Greg, 10 years awarded Windows MVP, here to help you.

UEFI is the modern BIOS that's been the standard for 10 years. All Windows installs should now be installed to UEFI. Legacy CSM mode is only for older installs, so that they can also boot on the same PC alongside UEFI. But new installs should not be installed in Legacy Mode. Installing in Legacy or CSM mode on a UEFI BIOS is like buying a new car and disabling all of the safety and performance features.

To install to UEFI, enable UEFI and disable Legacy in UEFI Setup, boot the media as a UEFI Device, delete all partitions down to Unallocated Space, then click Next to auto-create and format to GPT the needed partitions and begin - this makes it foolproof.

More about UEFI here:

https://www.howtogeek.com/56958/htg-explains-ho...

To convert Legacy installs to UEFI so they can take advantage of the advanced Security:

https://www.windowscentral.com/how-convert-mbr-...

Feel free to ask back any questions. Based on detailed results you post back I will have other suggestions if necessary.

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Trouble installing windows 7 on RAID in UEFI

As the title says, I'm trying to install Windows on a RAID array in uefi on my Maximus V Formula. When using legacy ROM I can install just fine but I go into CSM and change settings to UEFI only, I can build the array in the UEFI Raid driver (IRST tab in "BIOS") but the array does not show up in the boot menu and when I try to install windows (boot from UEFI DVD drive), The drive does not show up in the Windows install. The next thing I tried was to enable UEFI and legacy oprom in CSM, boot from UEFI DVD drive and install to the RAID array (probably detected by legacy oprom) and it will install. After first reboot, Windows Boot manager will show up as an option in the BIOS boot menu so I set that as first boot device and reboot. I will get to the starting windows screen and then BSOD (too quick to get codes) The last thing I tried was Changing to legacy mode and installing windows to a different drive. once installed, I initialized the Raid array as GPT and rebooted, changed csm back to UEFI only but they RAID array still doesn't show in the boot device list so I repeated the earlier process hoping that It might work because I had initialized as GPT but it still BSODs on starting windows screen. Any help or suggestions would be greatly appreciated