Transfer speeds using SATA HDD

[rebuilder]

Hi Forum!!

Long time not posting on here, but I'm glad to be back..

So I just went out and bought a few 4 & 8TB internal SATA drives for my builds.
after a few wrong formats I learned to use GPT to get all of my storage space.

I'm backing up all my movies from my smaller 1TB drives to the larger drives.
I'm noticing that when I first start the transfer it's cranking out at 186MB/SEC then it starts to slow down and settles in between 88.1-89.5MB/SEC

All storage drives are WD Black 1TB - 7200 RPM SATA 6 Gb/s 64MB Cache.
New drives are White Label 4TB & 8TB 7200RPM 64MB Cache SATA 6.0Gb/s (Enterprise Grade) 3.5" Hard Drives.

I'm using the on-board Serial ATA 3.0Gb/s ports directly.

Is this normal or how can I get a faster and more stable transfer speed?

 

[why_wolf]

That sounds correct to me. HDD usually average around 60-80ish MB/sec for long term file transfer speeds. They can see short burst of higher speeds but they cannot sustain them.