Ridiculous HDD Read/Write Speeds & Response Time

[RazePhalanx]

For a little while now, I've had an HDD (specifically, a 1TB Seagate ST1000DM003-1CH162) that I've been trying to use as additional storage on my PC.

The problem is that it has absolutely ridiculously slow read/write speeds (I'm talking single-digit KB/s sometimes), a near-constant 100% usage (examined through Task Manager), and an absurd response time of anywhere between 200-900ms (also through Task Manager). There are no programs that run off of this drive at any time (everything is installed on C:\, which runs at normal speeds and rarely at 100% usage).

Seagate's diagnostic tool shows no errors. Windows' chkdsk shows no errors. HD Tune's results are here (they basically show that disk health and temps are fine). MalwareBytes and AVG Free both come up with no detections. I've tried switching the SATA port the drive uses, completely reformatting the drive, and checking for updated motherboard drivers, all to no avail. Is there even anything I can do about this at this point?

Extra info:

• 
  OS: Windows 10 (v1607)
  RAM: 12GB DDR3 1600
  HDD in question: 1TB Seagate ST1000DM003-1CH162

 

[scout_03]

did you try to use another sata cable on it from motherboard also when was the last time you made defragmentation on it and see it is still have space for that .

 

[RazePhalanx]

did you try to use another sata cable on it from motherboard also when was the last time you made defragmentation on it and see it is still have space for that .

Defragmenting did seem to work, although I tried it a couple weeks ago and it made no change to any of the problems. Will update thread if problems persist.

UPDATE:
After 2 days, the HDD in question has returned to having low read/write speeds and high response times, although not nearly to the extent as before (200-550 kb/s and 200-500 ms when trying to watch a recorded 2 minute long video saved onto it). Defragmenting again has done nothing this time.