Question BIOS Booting from Non-OS Drive/Cannot Format Drive, Whilst OS is on another?


Dec 10, 2013
Hiyo, Tom's Hardware folks. Been a long time.

I'm looking for some assistance after having installed a new MOBO (Asus TUF Z390-PRO) and CPU (i9-9900k) onto a system. After rummaging with the system as it was for a day, I decided to make the decision to do a fresh Windows install (while buying a key because goddamn reauthorization wasn't working). After sorting a bunch of drivers that weren't automatically acquired, I realized that the BIOS was directing the boot from my secondary drive. I have three separate drives:

120GB SSD (Primary; OS/Base Programs (1/C: ))
1TB SSD (Secondary; Gaming/Storage (0/D: ))
2TB SHDD (Tertiary; Storage (2/E: ))

My Operating System is in fact installed on my C: drive. Due to an issue with admin permissions and folders I can't be rid of, I've decided to do a format on both D: and E: drives (while backing up intended content onto an external to drag back after). However, I was unable to format the D: drive. Checking the BIOS, I found that attempting to boot directly from C: got me a 'no OS found' error, telling me to Ctrl+Alt+Del my ass back to BIOS and pick another drive. So I can't boot from my Windows drive at all, it says no OS. This is what I get in the disk management window:

I'm guessing 'System' being on Disk 0 (D: ) is the reason I can't format it, but there's literally nothing on there to suggest a redirect for the OS to go to Disk 1 (C: ). The unallocated space on Disk 0 can't be accessed, regardless of what I do. Could it be something in there?

Any help is very greatly appreciated.

Thank you, Tom's Hardware.

Edit: To add onto this, I don't care about any loss on D:/E: drives, as I'm happy to reformat them both via a Windows Creation Media USB. I just want the system to run through the C: drive on boot-up.
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