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Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
Since I've upgraded my iMac 27" 2017 to Samsung 860 PRO 1 TB SATA along with OWC in-Line Digital Thermal Sensor, I keep hearing like similar to helicopter blades sounds.

I've attached a video of the noise experienced. Apologies of the clock ticking in the background 😄

Thank you in advance

 

komatsu

macrumors 6502a
Sep 19, 2010
547
45
The only moving part inside an iMac is the fan.

That possibly sounds like a fan but one that is stuck.

Can you download a utility such as iStat to get a reading of rotational speed of your main system fan?
 
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mdgm

macrumors 68000
Nov 2, 2010
1,665
406
I didn't think the 2012 and newer Macs needed the OWC in-Line Digital Thermal Sensor?

Edit: Hmmm. It seems it is used on the 27” but not the 21.5”.
 
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chscag

macrumors 601
Feb 17, 2008
4,622
1,946
Fort Worth, Texas
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Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
I am not sure if its the OWC in-Line Digital Thermal Sensor because I had the Samsung EVO SSD prior to installing the PRO version and on that one, I didn't have the OWC sensor installed. It didn't make any of these noises but when I installed the sensor along with the new SSD it makes these noises look like as @komatsu mentioned its coming from the fan
 

Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1

Attachments

  • CleanShot 2020-12-26 at 09.43.50@2x.jpg
    CleanShot 2020-12-26 at 09.43.50@2x.jpg
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chscag

macrumors 601
Feb 17, 2008
4,622
1,946
Fort Worth, Texas
First, I would remove the OWC Temp Sensor as it's not needed, and then use the Fan Control app to keep the fan at system set value.

If it appears things are getting too hot, (they shouldn't) you can always set the fan to follow the sensor reading.

It appears that you also have the original Apple 32GB SSD that came with the machine as part of the Fusion drive. I'm not sure if that makes any difference though.

I use Macs Fan Control on my iMac (same as yours) but my machine came with an Apple 512GB SSD, no Fusion drive. I keep the fan at system set. (normally around 1200 RPM)
 
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DeltaMac

macrumors G5
Jul 30, 2003
13,750
4,574
Delaware
MacsFanControl lets you increase the speed manually.
Try that, and you may find out the fan is your issue. The sound should change with the fan speed.

I also wonder if something is caught in the fan blades, maybe even a wire just barely touching the moving fan, and making that noise. Again, changing the speed of the fan manually should make sure that the sound is actually coming from the fan. (I don't see any other possibility, but, it's good to pin down the source of a mechanical noise!)
 
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Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
First, I would remove the OWC Temp Sensor as it's not needed, and then use the Fan Control app to keep the fan at system set value.

If it appears things are getting too hot, (they shouldn't) you can always set the fan to follow the sensor reading.

It appears that you also have the original Apple 32GB SSD that came with the machine as part of the Fusion drive. I'm not sure if that makes any difference though.

I use Macs Fan Control on my iMac (same as yours) but my machine came with an Apple 512GB SSD, no Fusion drive. I keep the fan at system set. (normally around 1200 RPM)
If I open it up again to remove the QWC Temp Sensor would you recommend me to take the Apple 32GB SSD blade out and replace it with a 1TB SSD blade along with 1TB SSD?
 

Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
MacsFanControl lets you increase the speed manually.
Try that, and you may find out the fan is your issue. The sound should change with the fan speed.

I also wonder if something is caught in the fan blades, maybe even a wire just barely touching the moving fan, and making that noise. Again, changing the speed of the fan manually should make sure that the sound is actually coming from the fan. (I don't see any other possibility, but, it's good to pin down the source of a mechanical noise!)
Yes, you're right because when I increase the fan speed, the noise merges with the other fan. But as soon as it comes back to 1200 rpm, it makes that noise again. Not sure if there is anything stuck or hitting the fan because I checked everything before closing it.
 

chscag

macrumors 601
Feb 17, 2008
4,622
1,946
Fort Worth, Texas
If I open it up again to remove the QWC Temp Sensor would you recommend me to take the Apple 32GB SSD blade out and replace it with a 1TB SSD blade along with 1TB SSD?
I'm not sure that would work. Someone else can chime in here that maybe has done the same thing and give you their recommendation. The problem as I remember it from other posts is that there is no way to connect both the SSD and blade SSD in the same configuration as was with the fusion hard drive and the 32GB blade SSD.
 

Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
I'm not sure that would work. Someone else can chime in here that maybe has done the same thing and give you their recommendation. The problem as I remember it from other posts is that there is no way to connect both the SSD and blade SSD in the same configuration as was with the fusion hard drive and the 32GB blade SSD.
Oh thanks for the reply anyway.

There is this person, who managed to do it.

I am not sure, if it’s legit since he didn’t comment afterwards of how he made it work.
 

DeltaMac

macrumors G5
Jul 30, 2003
13,750
4,574
Delaware
Yes, you're right because when I increase the fan speed, the noise merges with the other fan. But as soon as it comes back to 1200 rpm, it makes that noise again. Not sure if there is anything stuck or hitting the fan because I checked everything before closing it.
What "other fan" are you talking about?
Your 2017 iMac has only one fan, and you say that you hear the noise more when it is @ 1200 rpm, which is essentially at idle. Usually, annoying fan noise comes from a fan running at some speed above idle, or even going to max speed. And, that's often a problem with the temp sensor (hence a reason for the OWC temp sensor solution), but extra noise @ idle speed doesn't "sound" correct for a fan problem.
 

Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
What "other fan" are you talking about?
Your 2017 iMac has only one fan, and you say that you hear the noise more when it is @ 1200 rpm, which is essentially at idle. Usually, annoying fan noise comes from a fan running at some speed above idle, or even going to max speed. And, that's often a problem with the temp sensor (hence a reason for the OWC temp sensor solution), but extra noise @ idle speed doesn't "sound" correct for a fan problem.


Apologies, my mistake, I meant the main fan.

Would you recommend for me to open it up and remove the OWC temp sensor?
 

mdgm

macrumors 68000
Nov 2, 2010
1,665
406
I'm not sure that would work. Someone else can chime in here that maybe has done the same thing and give you their recommendation. The problem as I remember it from other posts is that there is no way to connect both the SSD and blade SSD in the same configuration as was with the fusion hard drive and the 32GB blade SSD.
I haven't done it myself.

In the 27", you can only install a SATA HDD/SSD if there was a HDD installed at the factory (either HDD or Fusion Drive). You can always install a blade SSD whether or not it was installed at the factory.

With the 21.5" you can only install a SATA HDD/SSD if there was a HDD installed at the factory (either HDD or Fusion Drive) and you can only install a blade SSD if there was a SSD installed at the factory (either SSD or Fusion Drive).

So any iMac that had a Fusion Drive installed at the factory or in the case of the 27" a Fusion Drive or just a HDD, can have both a SATA SSD and blade SSD installed.

Apple manufactured logic boards in such a way that for e.g. a 21.5" model with just a HDD, a blade SSD couldn't be installed. There isn't the connector for it.

There may be some other limitations as to whether a drive is compatible, for instance OWC's Aura Pro X2 isn't compatible with late 2015 iMacs. Perhaps that might be related to boot rom updates for the 2015 iMacs failing to be installed for a number of those Macs.

Before installing 3rd party drives it would be recommended to update the bootrom to the latest version. The latest version can be found in security updates for the previous 2 versions of Mac OS or software updates for the current version, so Security Updates for Mojave and Catalina and updates to Big Sur. For a number of Macs there have been bootrom updates improving compatibility with 3rd party NVMe SSDs fixing hibernation issues.
 
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Medic28

macrumors newbie
Original poster
Dec 11, 2020
14
1
I haven't done it myself.

In the 27", you can only install a SATA HDD/SSD if there was a HDD installed at the factory (either HDD or Fusion Drive). You can always install a blade SSD whether or not it was installed at the factory.

With the 21.5" you can only install a SATA HDD/SSD if there was a HDD installed at the factory (either HDD or Fusion Drive) and you can only install a blade SSD if there was a SSD installed at the factory (either SSD or Fusion Drive).

So any iMac that had a Fusion Drive installed at the factory or in the case of the 27" a Fusion Drive or just a HDD, can have both a SATA SSD and blade SSD installed.

Apple manufactured logic boards in such a way that for e.g. a 21.5" model with just a HDD, a blade SSD couldn't be installed. There isn't the connector for it.

There may be some other limitations as to whether a drive is compatible, for instance OWC's Aura Pro X2 isn't compatible with late 2015 iMacs. Perhaps that might be related to boot rom updates for the 2015 iMacs failing to be installed for a number of those Macs.

Before installing 3rd party drives it would be recommended to update the bootrom to the latest version. The latest version can be found in security updates for the previous 2 versions of Mac OS or software updates for the current version, so Security Updates for Mojave and Catalina and updates to Big Sur. For a number of Macs there have been bootrom updates improving compatibility with 3rd party NVMe SSDs fixing hibernation issues.

Thank you for your reply, I've checked my bootrom, and it's on the lastest version 2.41f2.

I think you're right. I need to remove the OWD temp senor and clean the fan area by checking any obstruction.
 
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