Problem with sudden slow SSD

[ebmaurer]

Hello,

since a while, I got a problem with my Macbook where my 9 month old SSD is all the sudden very very slow.

The details: Macbook Pro 9,2 (2012), 9 month old Samsung 860 EVO (was working since day 1 super fast until now), Mojave 10.14

I didn't change anything, it just went from superfast to super super slow.

I installed my old HDD and now a brand new SSD as external drive and all is normal. If I am putting it as my internal drive, in Recovery Mode, it's again very slow to react and even won't let me install the OS... showing 15 hours...

Whenever I have the SSD internal, nothing works almost and if, then very slow. I swap to the old HDD and use the SSD externally, all good.

What could it be?

Thank you

 

[CoastalOR]

I would suspect that the SATA cable that connects to the internal drive needs to be replaced from the symptoms that drives work okay external and not when internal.

MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement

Use this guide to replace a broken hard drive cable. The hard drive cable also contains the sleep LED and the IR sensor.

www.ifixit.com

 

[ebmaurer]

Hi and thanks.
But why is it working without any problems when having the HDD in? Only with the SSD it’s slow.

 

[CoastalOR]

Hi and thanks.
But why is it working without any problems when having the HDD in? Only with the SSD it’s slow.

The SATA cable can degrade due to age and wear such that it can still handle the slow data rate and demands of a slower HDD, but not the faster data of a SSD.

 

[chrfr]

Hi and thanks.
But why is it working without any problems when having the HDD in? Only with the SSD it’s slow.

I've seen this many times with the 2012 MacBook Pro. The cable seems to go out of tolerance for the SSD's performance, so replacing the cable will solve the problem.

 

[Fishrrman]

One more vote to replace the internal drive ribbon cable.
Go to ifixit.com to see what's involved and get the part number.
You can either buy the cable from them or get it online.
A simple change-out since you already know how to "go in" and change the drive.

I sense that a cable replacement will "clear up" the problems you've been having immediately...

 

[ebmaurer]

Replaced the internal drive ribbon cable and now it’s fast and working but now got another problem with TM backup, which installs backup but freezes at startup with 100% bar... did all the usual to fix but nothing. Will open a new thread.
Thanks