I've got a 250GB SSD for my OS (Samsung EVO) and a 2TB SSHD (Seagate Firecuda). After reading the mobo manual (ASRock Z370 Extreme4) I'm still not sure which connectors to use.. It states the following picture:
I think I'm currently using SATA3_A1 & SATA3_0 (or SATA3_A2 & SATA3_1, not currently at home) and the SSHD is being shown up as a removable device. I know there is possibly this: https://support.microsoft.com/en-us/help/3083627/internal-sata-drives-show-up-as-removeable-media to fix that, but I'd rather switch connectors if that fixes the problem too.
I think I'm currently using SATA3_A1 & SATA3_0 (or SATA3_A2 & SATA3_1, not currently at home) and the SSHD is being shown up as a removable device. I know there is possibly this: https://support.microsoft.com/en-us/help/3083627/internal-sata-drives-show-up-as-removeable-media to fix that, but I'd rather switch connectors if that fixes the problem too.