Kind of an odd question in my mind as I always thought a hard drive plugged into the motherboard SATA ports would be faster and more consistent speed transfer compared to USB but im seeing otherwise on my setup.
I was waiting for a day off to move my 2 new WD Red Plus 12tb drives into my PC Case and had them connected through 2 different Sabrent 3.0 external enclosures and the write speeds were almost dead flat on both between 230-250 MB/s. Now that they are in my PC connected through SATA cables to the motherboard the write speeds are jumping all over the place from a handful of MB/s to 200MB/s id guestimate averages in the 120's.
Im backing up large media files between 10-60gig's each so its not like the head is starting and stopping non stop with small files.
I made sure my mobo drivers are up to date with same results. My system is an MSI X570 Unify, Ryzen 9 5900x, 32gb ram.
Is this considered normal?