[SOLVED] I can't boot without csm enabled.

Sep 15, 2019
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I have windows 10 installed on a gpt disk (ssd) but i can't boot without csm enabled,if i try to it just takes me to BIOS and doesn't show my ssd as a boot option.
I want to be able to fastboot hence I want to be able to disable csm.
 
Can i fix this without reinstalling windows?
Yes. It's possible.
You will have to create a new bootloader partition on your nvme ssd and then change bios boot options accordingly.
Execute from elevated command prompt, regular command prompt will give out error on last step.
(https://winaero.com/blog/how-to-open-elevated-command-prompt-in-windows-10/ )

diskpart
list disk
select disk 1
(select 476GB disk)​
list partition
select partition x
(select 476GB partition, x is 1 or 2)​
shrink desired=500
create partition efi
format fs=fat32 quick
assign letter=H
exit
bcdboot c:\windows /s H: /f UEFI
After this is done, reboot into BIOS and change boot options, to boot from Windows Boot Manager on SSD.
 
Reactions: Hasan777

Colif

Win 10 Master
Moderator
Are you sure its a GPT drive?

can you show me a screenshot of disk management?
right click start
choose disk management
expand the window to show all columns
take screenshot and upload to image sharing website and show link here.

What motherboard do you have?
 
Windows on your pc is installed in legacy mode (not UEFI). You can see it in your screenshot #3 (BIOS mode).
So you can not disable CSM.

You installed windows, while HDD was connected. Bootloader (579MB system active partition) either was existing on HDD or
was created there there during install.
That's why, it's recommended to have only single drive connected during install.
 

Joakim Agren

Proper
Sep 5, 2019
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115
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Before trying anything else try switching the SATA ports between the 2 drives. So that your primary boot drive becomes DISK 0. See if that fixes it...
 

Joakim Agren

Proper
Sep 5, 2019
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Did you even care to look at the screenshots? No. MBR2GPT will not fix this.
When I bought my current GPU the Sapphire Nitro+ RX580 8GB GPU I could not get it to boot on my current 2500K Sandy Bridge system from 2011. Turned out that was because I had installed Windows in Legacy mode and used MBR whilst this card requires UEFI Boot. So I was advised to use the MBR2GPT tool and then switch from Legacy (CSM) to UEFI in my BIOS and that fixed it for me and I was able to use the card. So why should it not fix it for the thread starter? It is my understanding the MBR2GPT tool will remove the MBR from the drive in question and then in that article I linked there is also mentioned that you also need to enter BIOS to change the settings. Should these 2 things not fix the problem if so why?
 
Can i fix this without reinstalling windows?
Yes. It's possible.
You will have to create a new bootloader partition on your nvme ssd and then change bios boot options accordingly.
Execute from elevated command prompt, regular command prompt will give out error on last step.
(https://winaero.com/blog/how-to-open-elevated-command-prompt-in-windows-10/ )

diskpart
list disk
select disk 1
(select 476GB disk)​
list partition
select partition x
(select 476GB partition, x is 1 or 2)​
shrink desired=500
create partition efi
format fs=fat32 quick
assign letter=H
exit
bcdboot c:\windows /s H: /f UEFI
After this is done, reboot into BIOS and change boot options, to boot from Windows Boot Manager on SSD.
 
Reactions: Hasan777

Joakim Agren

Proper
Sep 5, 2019
142
20
115
13
Because OP has 2 drives.
Drive 0 is MBR and contains bootloader, Drive 1 is GPT and contains windows.
MBR2GPT can not operate in this situation. It works only, if windows and bootloader is on same drive and the drive has MBR partitioning.
Thanks for this reply! After reading up on this further I see that in this situation when there is 2 drives involved it will indeed not work as I was expecting! I figured since this tool is smart enough to remove a MBR partion it should also create a new EFI one instead. Strange that they design a tool like that. Knowing what I know now, my former advice would only lead to trouble and prevent the machine from booting at all since no boot loader can be found. So good that you corrected me so that I could read up further on this.
 
Sep 15, 2019
5
0
10
0
Yes. It's possible.
You will have to create a new bootloader partition on your nvme ssd and then change bios boot options accordingly.
Execute from elevated command prompt, regular command prompt will give out error on last step.
(https://winaero.com/blog/how-to-open-elevated-command-prompt-in-windows-10/ )

diskpart
list disk
select disk 1
(select 476GB disk)​
list partition
select partition x
(select 476GB partition, x is 1 or 2)​
shrink desired=500
create partition efi
format fs=fat32 quick
assign letter=H
exit
bcdboot c:\windows /s H: /f UEFI
After this is done, reboot into BIOS and change boot options, to boot from Windows Boot Manager on SSD.
Thank you very much for the help,everything works perfectly now.
 
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