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.

@puzzlezaddict Thank you! I'll go ahead and download the game to this new computer for now. I can always move it to the external again if space becomes an issue.

Quick follow-up though: you said I'll have to copy the user folder from my old computer to the new one in order to keep save files, right? How exactly do I go about doing that? I've never usually cared about it before, but I have a legacy save going that I really don't want to lose.

@twalice97  On the old computer, open Documents > Electronic Arts, right-click on the Sims 4 folder, and select Copy.  Then open the external drive, right-click in the empty space, and select Paste.  If you already have a "The Sims 4" folder there, create a new folder first and paste the Sims 4 folder inside that so things don't get confused.

Once you've launched the game on the new computer and verified it's running properly, plug in the external and start copying files from saves and Tray from the Sims 4 folder on the external to the Sims 4 folder on your new computer.  If you have mods or custom content, you can copy over those too.  Most of the other files are extraneous and will be recreated as necessary.  Here's a complete list, in case you're curious:

https://sims4.crinrict.com/eng/2014/09/user-files-explained/