So when I first got into PC gaming about 2 years ago I bought a pre-built system but later custom built my own rig. I used the HDD from the old PC because it had windows and all my stuff on it. I recently bought an M.2 drive (ADATA 128gb), did a fresh install of windows, signed into my Microsoft account, verified my account. At this point, I had done previous research about and was under the assumption I needed to get an empty drive to set up as a slave drive (I got an empty one off a friend) but it didn't work for some reason so I plugged in my old one and rebooted. Windows booted onto the m.2, AND my HDD was completely accessible. Launched discord, steam CS: GO and Google from it and it worked as if I was running windows off it. When I went to disk management it was showing that windows was only taking about 18gb of my M.2. So I'm just overall confused if I've missed something or done something wrong here.
Ryzen 5 2600 (Stock cooler)
EVGA 1080 FTW ACX
G Skill RGB 16gb (3000 mhz)
MSI B450 Tomahawk
ADATA XPG 128gb
Toshiba 1tb HDD
EVGA 650W Gold
Fractal Design Meshify C
