Windows 8.1 in legacy mode(MBR partitions) how to install windows 10 in UEFI mode(gpt partitions)?

Question

I have a laptop with windows 8.1 installed. My laptop supports UEFI but when i installed win 8.1 i converted GPT partitions to MBR and then installed win 8.1 as legacy(my bad, a long story).

But now i want to Install Win 10 and i want to get UEFI features so i need to install it in UEFI mode, but to do so i must convert my HDD to GPT. I saw in many articles that we can convert a selected partition to GPT using diskpart and convert to gpt commands while installing Windows.

so i need to know if that is possible?

1)can i keep my other partitions MBR and convert Only the C(windows) partition to GPT?

2)is there is a way i can install Windows 10 in UEFI mode converting HDD to GPT BUT WITHOUT LOOSING ANY DATA in other partitions(except for C) ?

p.s caps are only to emphasis words not to express shout or anger. Thank you.

Answer 1

GPT & MBR are drive partitioning schemes and are applicable at the entire drive level be it HDD or SSD. You can not have some partitions ‘MBR’ while others ‘GPT’!

If you use DISKPART to convert from MBR to GPT the command ‘CONVERT GPT’ needs to be preceded by ‘CLEAN’ command that deletes all existing partition.

There are third party tools that claim to do MBR <=> GPT conversion without data loss, I personally do not have any experience in using such tools. However users on this forum seem to have tried such tools. Refer this post for example.

• Raveen Athapaththu: Thank you. So basically it means that i cannot install windows 10 in UEFI mode unless i clean all partitions and convert to GPT which will cost me all my data.
• patkim: You can try third party tools that claim to do the MBR - GPT conversion without data loss. The hyperlink on 'this post' in answer above takes you to one such conversation on this forum.

Answer 2

pat2015's answer is correct; however, it is possible to convert a working BIOS-mode Windows install to boot in EFI mode. See this blog post, for instance. (I've not used this exact procedure, but I did once do something similar and it worked.) Be aware that such conversions are risky; you might end up with an unbootable installation. As a precaution, you should back up your personal data before attempting such a task. If you lack the means to do so, acquire it! Running without backups is risky, even in normal operation, since disks can fail, malware can wipe everything out, etc.

Another option is to install Windows 10 to another physical disk. You can then boot one Windows in one mode and the other in another mode. This may require either using the computer's (probably awkward) built-in boot manager or my own rEFInd boot manager. The latter will require changing its configuration in refind.conf: Uncomment scanfor and ensure the hdbios (or possibly biosexternal, if you use an external disk) option is enabled.

Really, though, the question is: Why do you want to EFI-boot Windows 10? Booting in EFI mode provides modest advantages at best. Given the hoops through which you'll have to jump to get it working on your current system, it's probably better to just stick with BIOS-mode booting for both of your Windows versions.