I would like to know on my new build 120 SSD and a 3T HHD so that I can install my games with most of the files are on the HHD and the games startup with the 120 SSD with the OS installed on it?
More about :setup build ssd primary hdd secondary games install
You will have to manually choose install locations, and programs like Steam often will not allow you to alter the main storage location (all or nothing for steam files on each drive). There are programs and techniques for doing this though, I am not sure if you can have certain steam files on 1 drive and others on another though. If you are asking for a way to keep the data files on the HDD and launch from the SSD, I don't think that makes sense and is not possible.
Personally, with games today accessing disk during gameplay, I'd install both the games and the OS onto the SSD so you don't have to wait as long for zoning, loading maps, etc. You can actually mount the 3TB drive to the Documents directory (without a drive letter) and store all your media there. I saw this week that you could get a 256GB Agility 4 for just $129. That's not much more than what a 120GB drive would cost.
When you download a file , software applications and games when the destination is shown during the download and install process you can change the location that you want it to go to and you would just need a shortcut on the desktop to open the game or program.
You can setup on a secondary drive a folder with sub folders and direct the instal to one of those sub folders and just have a shortcut telling Windows where it is.