Ssd replacent. Fan always speed loud


macrumors newbie
Original poster
Nov 29, 2017
Hi guys! I wanna replace my Imac 4k 2017 useless HDD with a SATA SSD. Since i know i would need a thermal cable to let the mac read the temps to regulate fan speed and system, can i do without that cable that cost about the same price as the ssd?

Maybe can i do something via software? Will my Imac be damage without this cable?!


vertical smile

macrumors 68040
Sep 23, 2014
Maybe can i do something via software?
I am not familar with the 2017 iMacs, but if they use the same HDD internal temp sensors as the mid-2011 iMacs, then they are probably the same.

You can use a software solution for the fan speed, but personally, I would just put in a cable with a external sensor while I had my iMac opened.

Will my Imac be damage without this cable?!
Are you asking if you don't use any solution, HW or SW, and just let the fans stay fast? If so, I don't think this would damage anything, except shorten the life of the fans.

If you are asking using a software solution to control fan speeds, could this cause damage? This is a guess, but maybe. If you are regulating the fan speed lower than what it needs to be, then this could damage stuff.

Just get the sensor, and you won't have to worry about it.
[doublepost=1561059356][/doublepost]Wait a sec, I am pretty sure the 2017 doesn't have the temp sensor.

I haven't opened it yet, but I have a Late 2012 iMac, and when I looked into replacing the Fusion Drive's HDD with a SSD, I don't recall having to get a temp sensor.

I would assume the 2017 is the same. I would still look into it, but I am pretty sure that there would be no software or hardware solution needed, because there is no HDD temp sensor.
Last edited:


macrumors regular
Sep 22, 2005
I've done 3 hard drive replacements on the modern slim-line imacs.

* 2012 21"
* 2013 27"
* 2017 27"

None of them have had temp sensors on the drive like the older thicker ones. You simply swap the drive out, nothing else to it.


macrumors 68000
Oct 14, 2018
The Sillie Con Valley
The 4K shouldn't as you've been told..

can i do without that cable that cost about the same price as the ssd?
Since the sensor for the 27" costs $39, this makes no sense.

Those are only for 27-inch iMacs.
Normally, the 2015-on doesn't need it. There are certain tests that, if run, will peg the fans if the sensor is missing. Workaround: Don't run those tests.