Question SSD shows in bios & disk manager but not explorer

Jan 14, 2020
Hey I just built a PC that has a 500gb M.2 which I installed Windows 10 on) a 2tb ssd hard drive and 4tb mechanical drive (all sata) I'm having two issues:

Since I flash the BIOS when I restart it goes immediately to bios unless I insert the USB drive it has a Windows bootable media on it. It worked before so I don't know if this is a bios issue or something that happened when I installed other drivers.

Second, if I do boot from USB I can see all three drives in BIOS and in the disk manager but only the M2 Drive has a drive letter assigned to it. It's also the only drive that shows up in Windows Explorer. I tried formatting all the drives using diskpart but I'm not able to assign Drive letters. It says no volume is present.

I've read a bunch of forums and exhausted my Google abilities, any ideas or leads? Much appreciated!