Question Installed new CPU, now Windows only boots in Legacy mode ?

[jpindal]

I upgraded my CPU to a Ryzen 5 5600X (before doing so, I updated BIOS by downloading the latest version). However, after the update, I could only get to the BIOS main screen and Windows didn't boot. Then I tried switching from UEFI to CMS, which was a success. However, now it takes Windows a long time starting up, and I'm not sure about the overall performance of applications either.

I don't know much about these modes. Is there a drawback using CMS permanently (other than Windows loading longer than usual)? What could be causing the UEFI mode not working?

 

[Lutfij]

Welcome to the forums, newcomer!

What motherboard are you working with? Did you clear the CMOS after you'd verified that the BIOS was flashed successfully to the latest version?

 

[jpindal]

Welcome to the forums, newcomer!

What motherboard are you working with? Did you clear the CMOS after you'd verified that the BIOS was flashed successfully to the latest version?

MSI B350M Bazooka.

I didn't specifically clear CMOS, but I did try "Restore default settings" on BIOS menu after installing the new CPU. What it did was just set UEFI mode as the default boot mode, and then I had to change it back to CMS again to get Windows to boot.

 

[SkyNetRising]

I didn't specifically clear CMOS, but I did try "Restore default settings" on BIOS menu after installing the new CPU. What it did was just set UEFI mode as the default boot mode, and then I had to change it back to CMS again to get Windows to boot.

Please show screenshot from Disk Management.
(upload to imgur.com and post link)

If your system doesn't boot in UEFI ONLY mode, then it was installed in legacy mode.
You were never booting in UEFI mode before.
Use of CSM is a requirement for legacy mode.

 

[jpindal]

I read a bit more about CMS, and it seems that it should not affect the overall performance of the system except for the longer boot time. However, isn't it a 32-bit mode? Doesn't this affect system performance?

Please show screenshot from Disk Management.
(upload to imgur.com and post link)

If your system doesn't boot in UEFI ONLY mode, then it was installed in legacy mode.
You were never booting in UEFI mode before.
Use of CSM is a requirement for legacy mode.

The Windows boot time increased significantly, which seems to suggest that UEFI was the main mode before?

 

[SkyNetRising]

I read a bit more about CMS, and it seems that it should not affect the overall performance of the system except for the longer boot time. However, isn't it a 32-bit mode? Doesn't this affect system performance?

No. It doesn't affect anything regarding performance. Has nothing to do with 32bit/64bit.
Will make secure boot unavailable though.

And it's CSM ( Compatibility Support Module ), not CMS.

 

[jpindal]

>However, after the update, I could only get to the BIOS main screen and Windows didn't boot.

If system hangs at Windows boot and not before, suspect would be Windows, ie you shouldn't have to change BIOS settings.

If you have a spare drive (HDD/SSD), temporarily pull boot drive and do clean Win install onto bare drive. If spare drive can boot normally, ie w/o CSM, suggest backup data and do clean Win install on boot drive.

I should've been more clear, system automatically shows the BIOS main screen and doesn't start Windows boot (without CSM).

Is there any drawback to just keep using CSM? Updating the CPU was kind of a temporary solution, and I will probably build a new PC from scratch after a couple of years. So really would not want to go through reinstalling Windows and all programs.

 

[SkyNetRising]

Is there any drawback to just keep using CSM?

You still haven't presented us with requested screenshot.
Please show screenshot from Disk Management.
(upload to imgur.com and post link)

 

[jpindal]

You still haven't presented us with requested screenshot.
Please show screenshot from Disk Management.
(upload to imgur.com and post link)

While I appreciate your help, I think at this point it serves no purpose as I'm content with how the system is operating. However, if you, or anyone else, is aware of potential problems that CSM may bring long term, please let me know. Thanks!

 

[SkyNetRising]

I think at this point it serves no purpose as I'm content with how the system is operating. However, if you, or anyone else, is aware of potential problems that CSM may bring long term, please let me know. Thanks!

Purpose is - to determine if you're indeed booting in legacy mode or UEFI mode.
You haven't presented with any evidence of either.
If you're already booting in UEFI mode, then all this discussion is irrelevant.

 

[jpindal]

Purpose is - to determine if you're indeed booting in legacy mode or UEFI mode.
You haven't presented with any evidence of either.
If you're already booting in UEFI mode, then all this discussion is irrelevant.

In Windows, I can access System Information. There it shows BIOS mode as "Legacy". Would this be enough evidence?
Also, in general, it would be nice to know if using CSM has any drawbacks for long term use.

 

[SkyNetRising]

In Windows, I can access System Information. There it shows BIOS mode as "Legacy". Would this be enough evidence?

Yes. That means system is installed in legacy mode and you're booting into legacy mode.
CSM can not be disabled or system becomes unbootable.

it would be nice to know if using CSM has any drawbacks for long term use.

Already told you - Secure boot is not available because of legacy boot mode.
Also you can not upgrade to windows 11.