Re: Question about installing Sims 4 on new computer
@twalice97 I've moved your post to the Sims 4 PC tech section. There's nothing wrong with posting in Origin tech; it's just easier to go over Sims-specific issues here.
Anyway, with your new PC, I'd install Sims 4 on your internal drive if you have the space. You'll get better performance overall and it eliminates any potential complications with how Origin handles the install process or updating the game at a later time. As long as your internal drive has at least 100 GB free right now, or 200 if you have a giant pile of custom content, you should be fine. You can of course still install on the external if you want; it's just a question of personal preference.
Your saves and other user data are stored by default in Documents > Electronic Arts > The Sims 4 regardless of where you installed the game itself, and Documents will be on your C drive unless you moved it. So simply transferring the contents of the external drive to the new computer wouldn't bring over your saves; you'd need to copy that Sims 4 user folder to your new computer as well. Best practice is to install the game, load it once to make sure everything works, and then copy the individual files, e.g. the contents of the saves and Tray folders, rather than copying over entire folders.