I have recently built a new PC and it has 3 drives: two SSDs, and one HDD. Windows is only detecting the boot ssd that it is installed on, and not detecting any others. The motherboard BIOS is detecting them fine.
MOBO: Asus Z270 Prime-A
CPU: 7700k
Drives: Sandisk SSD Plus 120gb
Samsung 850 EVO 500gb
WDC-WD20EZRZ-00Z5HB0
MOBO: Asus Z270 Prime-A
CPU: 7700k
Drives: Sandisk SSD Plus 120gb
Samsung 850 EVO 500gb
WDC-WD20EZRZ-00Z5HB0