[SOLVED] New MOBO doesn't find old disk with windows

[klaflo]

Hello,
I have just bought a new mobo for PC which is ASUS PRIME B460M-A R2.0.
Mobo recognizes my old disk: Samsung SSD 850 EVO but doesn't find it as bootable media...
I've googled a bit and I have seen that I should maybe enable CSM mode but it's greyed out and disabled on this specific bios not sure why...
Then I've also read that disabling fast boot and secure boot could enable CSM mode to not be greyed out but it didn't help, it's still greyed out and also disk is not visible as bootable media...
When I plug this disk back to my old mobo everything works. Does anyone know what seems to be the problem?

Thank you in advance!

 

[Zerk2012]

When you installed windows was the old motherboard set to IDE or ACHI that must match.
Your going to really need to do a fresh install of windows anyhow.

 

[klaflo]

I don't remember to be honest is there a way to check?

 

[rgd1101]

what your old system spec?

 

[USAFRet]

Additionally, was the 850 EVO the only drive connected when you did the original install on the old system?
If not, the boot partition likely exists on whatever other drive was in the system.

In any case, though...new motherboard -> fresh OS install.