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#11
In the previous post I showed my boot options page. On it was CSM. If you expand CSM it gives you a brief description on the left to explain what the options mean. Mine is set to auto, which enables either one but allows you to install in legacy mode but gives most of the advantages of UEFI. I just select the SSD I want to boot from. It sounds like that is what you like. Yours may or may not be called the same, but it seems you should have similar options although called something else.