M.2 Operating System Boot

[kb5zue]

My Asus TUF Sabertooth 990FX 3.0 mobo supports a single M.2 drive.  From what I have read, I can use this as a boot device which is nice.  I would like to use this for booting but my question is, since I have not done this before and I only know what I have read here in the forums, what happens to the windows setup after installing the M.2.  I know to unhook my boot drive SSD before installing Windows, but my concern is when downloading or installing, how do I tell the/any download or install NOT to drop the files to the M.2 and to drop them to the SSD instead?  Looking at something like the Intel Optane: https://www.newegg.com/Product/Product.aspx?Item=N82E16820167427.  Just trying to figure out how this works because I don't want to fill up the NVME with a bunch of stuff, just the operating system (Win10 Home, 64bit).  Thanks to all that can help.  Reallly appreciate it.

[kb5zue]

Another quick question please.  Does the M.2 such as the Optane require a heatsink or cooling of any kind?

[TheRandomness]

You can't use Optane on the motherboard that isn't 200 series Intel (so like Z270, the Kaby Lake generation) or higher.

[Razor Blade]

The M.2 drive showes up like any other hard drive. Windows installs exactly the same as it would with a standard drive. When installing programs just change the directory to your second drive. Also change your default download and steam(if applicable) folder to your second drive. I do not run a heatsink on my Samsung M.2 but then again I don't hit the drive hard or anything. I use it for the OS and some programs. All the data read and write is done with the other drive and any larger file or archive storage is on my NAS with mechanical drives.