Old HDD Showing 100% Disk Usage After Installing SSD

[herewegoagain100]

After successfully installing the Renegade Fury SSD into my PC and booting from it, I noticed that my old HDD still shows 100% disk usage. I spend hours figuring out how to transfer and boot from the SSD and I eventually succeeded with a fresh install of Windows 10 using the Windows Media Creation tool. However, my old HDD is still being utilized when running games or apps, as it spikes to 100% while the SSD remains at 1% or 2%. Although I haven't experienced much lag on my PC due to the 100% usage, i'm worried to see it constantly maxed out. I suspect that the issue may be related to the system reserved partition being on the old HDD.
Even more, the 100% usage is reflected in the Performance tab of Task Manager, but not in the Processes tab. Is there a way to resolve this?