I will try to explain bcs my english is not really good.
I own 2 hard drives , 4 TB’s greens and one of them is really slow (slow writes slow reads)
things I 've tried:
1- different SATA cables
2- differents SATA ports
3- Asus M5A78L-M/USB3 motherboard (SATA II)
4- asrock z77 extrem 4
And everywhere one of them is really slow at benchmarks,