New build, asus z390 e mobo, 9700k, hp ex900 250gb m2, samsung 970 evo 500gb m2, samsung 860 ssd.
Unplugged sata ssd
entered Bios clear keys, secure boot to other os, csm disabled
Booted with windows 10 disk image on thumb drive. Selected the hp ex900 ( based off available space I assume...