I'm a bit lost in all this, except for kind of thinking that it shows X86 is a giant mess. First, doesn't Windows knows how to use NVME drives as NVME drives,

I'm a bit lost in all this, except for kind of thinking that it shows X86 is a giant mess. First, doesn't Windows knows how to use NVME drives as NVME drives, without going through some weird SATA compatibility layer? Second, if I'm reading you right, Windows also has bundled drivers for RST. It's just that the installer doesn't. Is that right? Are you saying that the Windows installer doesn't know how to use storage interfaces that the final installed Windows system would know how to use, and furthermore that those include storage interfaces that might be used for the boot drive? So in order to install, you have to get an RST driver and somehow load it into the installer, but after that the system will work? Because that sounds like a Windows problem more than a BIOS problem. You're installing your OS on reasonably vanilla storage[^1]. Why would you expect to have to download a driver from Dell at all? [^1]: Sort of vanilla. I don't know about this "RST" nonsense and am suspicious of anything that might make it hard to move a drive, or indeed an entire RAID array, to another computer or controller intact.