HGST Travelstar 2.5-Inch 1TB 7200RPM SATA 6GB/s Optical

I had this travelstar drive installed to replace the optical drive. At first it formatted no problem but then when i was copying files from an external drive the transfer speeds were extremely slow 4 gigs would take 3 hours. . I then tested transfer files from my Samsung SSD 850 pro (main drive) to the travelstar in the optical bay and still it was really slo 2 gigs 30 min.. Afterward the disk unmounted again so i I reformatted in disk utility under the partition menu Mac OS extended with GUID under the options and tried to copy files it was faster for a few minutes then slowed down and then unmounted again. I was concerned that it was the 6gb/s issue but when i check my system info it says: Vendor: Intel

Product: 6 Series Chipset

Link Speed: 6 Gigabit

Negotiated Link Speed: 6 Gigabit

Physical Interconnect: SATA

Description: AHCI Version 1.30 Supported

I can't mount the disk and when reformatting under partition/guid option it gets stuck at "waiting for disks to reappear" or if it completes it doesn't mount and is greyed out on the left.