MBP 1,1-10,2 HDD connecting at SATA II speed

[MacInTO]

I have a HDD that was connecting at SATA II speed in an iMac so I suspected it was going bad. I removed the HDD and tested in my 2012 15" Macbook pro. The iMac HDD also connected at SATA II speed in the MBP so I deducted it was the drive failing and I removed it. When I put the previous HDD back into the MBP, it also connect at SATA II speed. However, before removing it, I know it did connect at SATA III speed. I tried resetting the SMC and PRAM in the MBP several times to no avail.

Eventually, I gave up on the HDDs and I put a SSD into the MBP and it connected at SATA III speed.

How is it possible that a drive that one minute connected at SATA III could only connect at SATA II. Could the HDD from the iMac affect the connection speed of my HDD from my MBP or did it do something to the controller?

 

[Intell]

The HDD cables in 2010-2012 unibody Macbook Pros is known of having issues with it failing over time or when moved due to how the cable bends around a corner. Seeing the drive connect at a different speed may be a sign that it is starting to fail. I would recommend replacing the HDD cable and checking if the speeds have improved.

 

[MacInTO]

Thanks. That what I thought also. I will try a new cable.