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Cooling in the new 2020 27" iMac?

AlbertVila said:
I got my iMac 2020 (i7, Radeon Pro 5500 XT) last Friday. I can hear the constant high-pitched sound, all the time, when the fans are at 1200 rpm. To be clear, the sound is not the air flow, it's a 'flutter' done by the fan spinning. It comes from the inside. I have a laptop cooling pad and the fan does the exact same irritating sound (I turn it off as soon as the MBP cools down).

Most probably I'll return it, because after some hours in front of the machine my ears start to whistle. I don't mind the air flow, but I can't stand this high-pitched sound.

I'm thinking about getting a Mac Mini + the 5k UltraFine. What do you think about the 5k monitor? I've read plenty of bad things about it.
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The monitor is basically the same as the one in the iMac. The stand is not so good apparently but my main objection to your configuration would be the cost. The 5k UltraFine and an i7 image will cost iMac money but not deliver the same performance.

Maybe you should return it and order another one.
 
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rkuo said:
I wonder if anyone has tried rigging up some sort of baffle or muffler around the vents to absorb the sound. Seems like it should be possible.
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I've put a quite big acoustic panel right behind the iMac for a test. It helps a great deal, it was almost silent with that treatment. I still have to find out if its enough to put the panel right on the wall with the iMac sitting close to it.
 
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DRuser said:
I've put a quite big acoustic panel right behind the iMac for a test. It helps a great deal, it was almost silent with that treatment. I still have to find out if its enough to put the panel right on the wall with the iMac sitting close to it.
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Very nice! Channeling the vented air through a hollowed acoustic foam block could do some good. Just takes some creativity and willingness to experiment.
 
AlbertVila said:
I got my iMac 2020 (i7, Radeon Pro 5500 XT) last Friday. I can hear the constant high-pitched sound, all the time, when the fans are at 1200 rpm. To be clear, the sound is not the air flow, it's a 'flutter' done by the fan spinning. It comes from the inside. I have a laptop cooling pad and the fan does the exact same irritating sound (I turn it off as soon as the MBP cools down).

Most probably I'll return it, because after some hours in front of the machine my ears start to whistle. I don't mind the air flow, but I can't stand this high-pitched sound.

I'm thinking about getting a Mac Mini + the 5k UltraFine. What do you think about the 5k monitor? I've read plenty of bad things about it.
Click to expand...


wilberforce said:
I just received my 2020 iMac replacement for my 2014 iMac (first 5K 27" model), and can make side-by-side comparisons.
Mine is an i7 with 5500 XT.
The fan on the 2020 iMac is noticeably louder and more air flow than on the 2014, when both are running at 1200 rpm (according to MacsFanControl).
On my 2014 the fan at 1200 rpm is barely audible, and I have to put my ear close to the vent at the back to hear it, and can barely feel any airflow on my hand. (It has always been like this, from day one in 2014).
On the 2020 I can just hear it from the front of the machine (in a quiet room), and can easily feel much more airflow, at the same reported 1200 rpm.
If the reported rpm is correct (1200), it seems the fan design has been somehow changed to produce more airflow, perhaps with different fan blade shape or size - I don't know.
It is still a very quiet fan, and does not bother me, but it is a noticeable change.
Something to consider for those that are very sensitive to fan noise.
IMO the fan noise when running at minimum rpm is the most important consideration for noise: this is the condition for 99% of the time.
Everything else about the 2020 iMac is a welcome improvement over the 2014 - speed, screen, etc
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Hmm. I’m not alone. I have base model of 2020 iMac 27’ (i5 / 5300) and the fan is making rattling noise at idle (1200 RPM). Video recorded by iPhone 8 Plus near vents:

 
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DRuser said:
I've put a quite big acoustic panel right behind the iMac for a test. It helps a great deal, it was almost silent with that treatment. I still have to find out if its enough to put the panel right on the wall with the iMac sitting close to it.
Click to expand...

I have been using a pillow (between the iMac and back wall) for a week or so, and it does help. An acoustic panel is something I have started to research a few days ago as a potential permanent solution.

Which brand/model is the panel you have?
 
myjacob said:
So probably not worth return it and hope for a better unit :( What did u do ?
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Don't want to complicate it any further, however I have just received a replacement for the iMac I have purchased a couple of weeks ago. Same specification.

The new unit is a bit louder, the old one has a bit of noise at idle (louder than a 2017 i5 I had) generated by the air flow and the new one has the same air flow noise + additional noise generate by audible coil whine. The old one also has the coil while noise , however to hear it I have to press my ear against the chassis (back/right side, the ports side). The new one has the coil whine noise a lot more auditable, so I can hear it without much effort.
 
edib said:
Don't want to complicate it any further, however I have just received a replacement for the iMac I have purchased a couple of weeks ago. Same specification.

The new unit is a bit louder, the old one has a bit of noise at idle (louder than a 2017 i5 I had) generated by the air flow and the new one has the same air flow noise + additional noise generate by audible coil whine. The old one also has the coil while noise , however to hear it I have to press my ear against the chassis (back/right side, the ports side). The new one has the coil whine noise a lot more auditable, so I can hear it without much effort.
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So it could be even worse ... I won’t take risk probably. I’ve got perfect display without any bleeding. Your first unit was similar to mine or second one? I don’t hear anything which is similar to coil whine. Only airflow with this rattling sound.
 
My 8-core 5700XT iMac has audible fan noise at idle. My 2017 model was capable of being virtually silent at idle. Is this a thing?
 
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edib said:
I have been using a pillow (between the iMac and back wall) for a week or so, and it does help. An acoustic panel is something I have started to research a few days ago as a potential permanent solution.

Which brand/model is the panel you have?
Click to expand...

I've bought a few Basotect absorbers which are the standard when it comes to good absorbers in Germany. I'm not sure if they are available internationally. You are buying basically just a block of foam, it doesn't look very pleasing if you use it on it's own. However, there are many DIY videos out there to put these into a frame and put fabric around to hang it off a wall. Here is a link from Amazon UK:

www.amazon.co.uk

Self-Adhesive Basotect Sponge 5cm in Light Grey 120x60x5 cm 0.72 m2

ME PLAN DECO acoustic-foam-basotect decor is a soft foam material with high absorption capacity of noises. The raw material we use for our acoustic panels is the Basotect of the BASF company In particular, we highlight its fireproof characteristics ME PLAN DECO has a unilateral smoothing on all s...
www.amazon.co.uk
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
Sheza said:
My 8-core 5700XT iMac has audible fan noise at idle. My 2017 model was capable of being virtually silent at idle. Is this a thing?
Click to expand...
My 8-core 5700XT is basically silent for me. I do not have a wall behind my iMac though, so any sounds coming out of the back aren’t reflected by a wall.

There have been two times I thought I was hearing my iMac but it turned out to be the fan in my work laptop.

So far the only way to make my iMac audibly loud is to run Blender renders on the CPU. GPU-only renders in Windows don’t even get the fans going full speed.

I’m very happy with the lack of noise coming from my iMac. The fans didn’t even crank up while installing Windows.
 
PBG4 Dude said:
My 8-core 5700XT is basically silent for me. I do not have a wall behind my iMac though, so any sounds coming out of the back aren’t reflected by a wall.

There have been two times I thought I was hearing my iMac but it turned out to be the fan in my work laptop.

So far the only way to make my iMac audibly loud is to run Blender renders on the CPU. GPU-only renders in Windows don’t even get the fans going full speed.

I’m very happy with the lack of noise coming from my iMac. The fans didn’t even crank up while installing Windows.
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Hmm. Well, since this iMac is getting replaced (chipped aluminium) I’ll see how the replacement fares
 
ADGrant said:
The monitor is basically the same as the one in the iMac. The stand is not so good apparently but my main objection to your configuration would be the cost. The 5k UltraFine and an i7 image will cost iMac money but not deliver the same performance.

Maybe you should return it and order another one.
Click to expand...

Yes you are right: if I get the Mac mini and the 5k instead I will pay the same and get a much worse machine.

I don't think I'll order a new one if I return it though. Most probably it will have the same issue.

BTW my brother has an older iMac and it doesn't make the high-pitched noise. It's only air flowing.
 
myjacob said:
Hmm. I’m not alone. I have base model of 2020 iMac 27’ (i5 / 5300) and the fan is making rattling noise at idle (1200 RPM). Video recorded by iPhone 8 Plus near vents:

View attachment 949569
Click to expand...

Yeah that definitely sounds like a rattle, almost like the fan/blades are off balance. 👎
 
myjacob said:
So it could be even worse ... I won’t take risk probably. I’ve got perfect display without any bleeding. Your first unit was similar to mine or second one? I don’t hear anything which is similar to coil whine. Only airflow with this rattling sound.
Click to expand...

The first unit has only noise which is generated by airflow, no rattling no coil whine type of noise auditable from my sitting distance. The second unit has the airflow noise + rattling noise (the noise is closer to rattling than typical coil whine)
 
AlbertVila said:
Yes you are right: if I get the Mac mini and the 5k instead I will pay the same and get a much worse machine.

I don't think I'll order a new one if I return it though. Most probably it will have the same issue.

BTW my brother has an older iMac and it doesn't make the high-pitched noise. It's only air flowing.
Click to expand...

My 2020 iMac with the I9 and a 5700XT doesn't make a high pitched noise either. I would definitely notice if it did.
 
edib said:
Ok, just connected the new iMac. The true tone display is absolutely gorgeous !
The ambient room temperature is about 19C, the case was cold when I got it out of the box (9C) outside.
CPU cores about 26C, fan at 1200rpm, quiet room 29dB or so.

Not sure what they have changed as compared with the 2017 i5 model, however the fan in the new 2020 iMac is a lot more noticeable. It goes all the time. It is just a white noise, not very loud, however [Updated wording after a few hours) it can be noticeable and somehow distracting (as it is at ears level), however it seems like it can be manageable, see below. For me [Updated wording] there is a difference between the two, so Apple claim (as per the tech sheets and in my case) that the 2020 i7 is quieter than the 2017 i5 is not very accurate.

To be honest, I am not sure why the fan needs to run at all when the CPU temperature is 25C and the CPU is using 2W.

My advise is, if are sensitive to noise and work in a quiet environment the only way to find out if the new iMac is for you is to buy one, test it and then decide. If you already have an iMac you are happy with, keep it and enjoy. Lastly, don’t sell the one you have before trying and testing the new one, you might need it.

[Update]

I have already spend a bit of time with the new 2020 iMac (i7) and have updated the wording in my original post above, toning it down a bit.

It seems like what I am hearing as compared with the old 2017 i5 iMac I had is more air movement coming out through the vents (perhaps the fan has been "upgraded" and now can push more air out as compared with the older models). When I cover the vents I hear nothing. The noise can be somehow managed, I have simply placed a pillow between my iMac and the back wall (it is close to it, same as the old one) without covering the vents and the noise quieten a bit and also its sound signature has changed. It is now closer to what I had with the old iMac. The "noise" is still there, however I wound't call it distracting or noticeable. I am now looking for some acoustics absorption panels to be installed behind the iMac, so hopefully this will help a bit more.

There is also a bit of coin whine I have discovered, however that is only audible when I place my ear very close to the right/back of the iMac. I have since reconnected the computer, powered off some nearby devices and it seems like the noise has settled a bit. In both cases I couldn't hear if from the sitting position.

Please keep in mind that all of the above comments relate to the fan at idle speed (1200 rpm) with the CPU temperature around 37C (it was 25C when I first fired it up).

Not sure if that helps anybody, however I thought that the original post needed to be updated.
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Is it normal that my CPU temperatures are around 60° (C) on idle? I have i7 5700xt
 
I haven't had any issues with it on my new iMac. I tend to play emulator games and stuff that usually heats up on my MacBook Pro like crazy! But my iMac stays cool the whole time, even if I leave the game on for many many hours.
 
myjacob said:
Hmm. I’m not alone. I have base model of 2020 iMac 27’ (i5 / 5300) and the fan is making rattling noise at idle (1200 RPM). Video recorded by iPhone 8 Plus near vents:

View attachment 949569
Click to expand...
I think it's a bad fan. I had purchased a store model at first before I ordered my BTO. The store one with the high tier one with the i7 and 5500XT and it make the EXACT same noise especially when listening to it on the right side of the computer and in the back. I returned it and ordered a custom one instead as I wanted the 5700XT GPU. The new one does not make this noise. My guess is that the store ones were all made earlier to fill the stores for people who want the lower priced entry models to take home the same day. The BTO ones are built as they are ordered so may have a different batch of fans.
 
dsc888 said:
I think it's a bad fan. I had purchased a store model at first before I ordered my BTO. The store one with the high tier one with the i7 and 5500XT and it make the EXACT same noise especially when listening to it on the right side of the computer and in the back. I returned it and ordered a custom one instead as I wanted the 5700XT GPU. The new one does not make this noise. My guess is that the store ones were all made earlier to fill the stores for people who want the lower priced entry models to take home the same day. The BTO ones are built as they are ordered so may have a different batch of fans.
Click to expand...

Mine is a custom configuration and I have the bad fan :/
I guess I had bad luck
 
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