TECH My replacement Samsung 2TB has poor speeds, sawtooth pattern wtf

[Moloch]

My original drive died a few months ago and the drive Samsung sent to me is much slower and all the hdd benchmarks give me much slower speeds and a sawtooth test pattern for STR. I've tried multiple formats, using a GPT as well as a Mbr partition style(win7) and nothing has any effect on the speed of it. Any ideas?
For reference, original drive:

Replacement drive:

 

[dorkultra]

what do your s.m.a.r.t. diagnostics look like?

 

[dorkultra]

a few of my hard drives for comparison. i really haven't noticed any slowdowns

it could be an issue with your sata controller or the one built into the drive. have you tried a different sata cord and port?

 

[Moloch]

I tried a different sata cable (swapped it with a hdd I dont rly use) and used the native sata controller instead of my pci-e highpoint sata III controller and that fixed it. I've switched cables before and tried native sata controllor with no difference, so curious why it fixed it. The drive I swapped cables with doesn't exhibit the erratic STR pattern btw. The drive never produced any s.m.a.r.t errors btw.
My avg read speed is now within a few MB of the original drive, which was totally clean when I benchmarked it, I've put 200GB of data on the new drive.

 

[dorkultra]

on my dad's office computer, he was getting about 4MBps on one of the ports.

swapped out the cord and it made not difference. tried a different port and he was back to 120MBps+

i tried the port the following week and there was no problem for a few minutes, then it slowed down again