I recently got my second (well third) Hard drive up and working and I was wondering if there is a way how I can change it to be what my Current game drive is. Do I change my D:/ to something like H:/ and then my G:/ back to D:/ and then copy over my games form 'H:/' to the new D:/. Or am I just thinking to much and I should be right to just move them over to the G:/ and change the Steam download location 

C:/  OS/boot
D:/ Gaming (1 TB)
G:/ New Drive (2TB)

I'm not exactly sure on Steam. You could transfer the games over, but I have no idea if Steam would detect them when you try to play them. You can change the locations to where Steam games are installed, though. I have games on both of my hard drives.

You can move your Steam library. It's a bit slow and involved though.

First, if Steam still recognises the games on your old drive as installed, rename the folder your steam library is in. Then remove it from Steam's libraries. You can create a new library in Steam on the new drive, then copy the folders from OLD:\path\to\steamapps\common to NEW:\path\to\steamapps\common. Then in Steam, install each game and it will show you this:

Then it will only re-download any damaged or missing or modded files.

It will take a long time though since you can only do one at a time. I know since I'm doing this right this second with one of my steam libraries.

Spoiler

 

When I moved my Steam games, all I had to do was make a new steam library on the new drive and copy all of the games over to it. Then, after restarting steam, it recognized those games as installed. All it had to do was the "first time setup" for each game, no "discovering existing files" thing.

Note: I copied the entire steamapps folder, not just common. Some of the files in steamapps are simply for steam to know what games are installed in that location. If you do it that way, there's no need to redownload or install anything.

Note 2: Essentially this is the whole process:

1. Open Steam and create a new game library on the new drive.
2. Exit Steam
3. Move the entire steamapps folder from the old drive to the new Steam library location (either by cut/paste, or copy/paste/delete; you probably don't want the games in both locations when you start Steam again). Usually the new location will be called "SteamLibrary" or something. I'm not sure if it will already have a steamapps folder, if it does just merge them.
4. Open Steam. All of your games that were previously installed should still be installed. Whenever you launch one, it might perform the first time setup again.

One issue with this might be with the registry. You might end up having redundant entries there since you never actually uninstall the games from the old location. I fresh installed Windows after this process, so it wasn't a problem for me.