My pc (am4 ryzen cpu w/msi tomahawk mobo) 1 m.2 HD , win11, use it everyday. I want to add a 2nd HD (sata ssd but not m.2 interface) with its own windows 11 OS. I would rarely use this drive so don't want to buy a second PC. This 2nd HD will be used for downloading torrent and possibly running cracked software. Does going into cmos before booting and disabling the 2nd HD every time I need to use the computer, and vice versa when I need to boot the 2nd OS? Would this be 100% fail proof against infecting my main OS HD? Thanks you.
No, 100% isn't possible, not even then. There is actually Malware able to infect the PC firmware (BIOS/UEFI) or devices' firmware flash area. Even the modern CPU has flashable storage. Not very probable, but a small possibility.
Virtualization is the answer. Run the other OS on a virtual environment and whatever happens inside it, it should not cause any harm to your main system Welcome to MDL