None-OS storage being used to load files instead of OS storage

[Kallakix2015]

I have Windows 10 installed on an SSD, a secondary SSD for games and a HDD for files. I keep noticing that if I open the downloads folder or try and save files to the desktop, the PC will use the HDD instead of the SSD. I noticed because the HDD was going to sleep automatically, I'd open a folder and it would do nothing until the HDD booted up. I've now turned the auto-sleep to a few hours instead of the default 20 minutes.

Why would windows be using a none primary piece of storage to load things from? I never installed any OS related files on there, but it keeps going to it for certain things.
I extended the sleep time for the HDD because people were saying frequent boot ups and shut downs are strenuous for hard drives.

Does Windows automatically save files to the largest storage and should a HDD sleep timer be longer or shorter?

Thank you.

 

[CondMan]

Hi, I had that similar problem a coupla years ago.
I found out that I could change the Download folder to another location.
I used the new location as the Desktop(C Drive-SSD in your case).
It was quite easy to do but I cannot remember the details.
If you look it up on google with 'Change Download Folder on Win etc' you'll get a few links to explain it, it is fairly straightforward & only needs a few Clicks.