Recent 27" iMacs are NOT silent

[motrek]

I am in a room with no road noise and no central air. If I put my ear right next to the iMac vents I can hear the air moved by the fan as it flows past obstructions, but not the fan itself. Mine also claims 1200 RPM. I cannot hear anything at idle in normal use at normal distances from the vents. I _can_ hear my (8 feet away) DVR fans come on and spin slowly when the DVR does garbage collection or compaction or whatever it's doing late at night.

I do not think you are being overly picky -- perhaps a bit unrealistic to *expect* a high performance desktop system to be as silent as an old Mac mini or a five year old laptop.

I do disagree with your premise that it depends on the situation. I'm proposing a different one: it depends on the luck of the draw if they install a loud fan, a practically silent one, or one somewhere in the middle.
...

It's possible. The iMac I'm using to write this is the only one I've ever owned, so I can't say one way or the other. But my gut feeling is that the sound I hear from it at 1200 RPM is air turbulence more than the fan itself. I've done the firmware "hack" to reduce the fan speed to 1000 RPM and, at that speed, I find it to be inaudible. Which I think is an indication that the fan noise is more air turbulence than noise from the motor. Which would mean that all similar iMacs make the same amount of noise.

Yes, my iMac is a "high performance desktop" but at idle, it doesn't use that much more power than my MacBook. The fact that it runs fine with the fan at 1000 RPM instead of 1200 RPM is an indication that it doesn't really NEED to make much noise at all. I think what probably happened is that Apple designed the cooling system in 2012 and didn't revisit it since then, even though more recent chips run cooler at idle.

 

[CheesePuff]

It's possible. The iMac I'm using to write this is the only one I've ever owned, so I can't say one way or the other. But my gut feeling is that the sound I hear from it at 1200 RPM is air turbulence more than the fan itself. I've done the firmware "hack" to reduce the fan speed to 1000 RPM and, at that speed, I find it to be inaudible. Which I think is an indication that the fan noise is more air turbulence than noise from the motor. Which would mean that all similar iMacs make the same amount of noise.

Yes, my iMac is a "high performance desktop" but at idle, it doesn't use that much more power than my MacBook. The fact that it runs fine with the fan at 1000 RPM instead of 1200 RPM is an indication that it doesn't really NEED to make much noise at all. I think what probably happened is that Apple designed the cooling system in 2012 and didn't revisit it since then, even though more recent chips run cooler at idle.

Yes, you overriding the default values and running the fan at a lower then its default low setting means you know more then the engineerings who designed, tested and built the system. I still can't believe how long this thread is about such a topic, unless I have the worlds quietest iMac.

 

[Lankyman]

You are joking, right? Spinning hard drive is NEVER silent. How can you even say that? FD is the worst possible thing that Apple ever gave us. No thank you

And no, its not silent regardless of what you say. The spinning mechanism etc. inside a FD is making tons of noise! Not silent at all!

That is your personal opinion. One of the few benefits of getting older is you don't hear as well, so to me my iMac is silent. As for you comment on FD. I have a full SSD iMac and yet having one I still chose a FD for my latest iMac. I wanted fast storage plus large storage capacity for large files/folders such as iTunes, photos, videos. The FD provides all of this and is a great combo. I would definetley chose such an option again were it offered.

 

[Freida]

It is not my opinion, its a fact. The spinning mechanism inside is making noise. (Do you know how traditional HDD work?)
Unless you were talking about the other part. Regardless, FD is (as we say around here) - For Fusion Sake. FD is a crap product all around. Its prone to failure, its slow and it is limiting in many ways. The fact that you defend it tells me that your usage is not very demanding and you value storage space over everything else.
Regardless, FD is dead and we are very happy about it. One of the worst things from Apple for iMac.
Maybe one day you will see

That is your personal opinion. One of the few benefits of getting older is you don't hear as well, so to me my iMac is silent. As for you comment on FD. I have a full SSD iMac and yet having one I still chose a FD for my latest iMac. I wanted fast storage plus large storage capacity for large files/folders such as iTunes, photos, videos. The FD provides all of this and is a great combo. I would definetley chose such an option again were it offered.

 

[motrek]

Yes, you overriding the default values and running the fan at a lower then its default low setting means you know more then the engineerings who designed, tested and built the system. I still can't believe how long this thread is about such a topic, unless I have the worlds quietest iMac.

I didn't say that I "know more" than Apple engineers about their own cooling system. But, odds are good that they designed the cooling system to meet their own specifications in 2012 and decided not to revisit it, or they decided not to add variations to their product line that are arguably unnecessary.

Because really, every thin 27" iMac since they came out in 2012 has had its minimum fan speed configured to be 1200 RPM. Even though they've shipped with dozens of different CPUs and GPUs over the years. What are the odds that 1200 RPM is always exactly the right minimum fan for every single variation?

Believe me, the last thing I wanted to do was damage my expensive iMac by running the fan too slow and having something overheat. I spent a lot of time comparing before/after temperatures with Macs Fan Control, checking all 20 temperature sensors in my iMac to see if the lower fan speed was causing anything to run hotter. It wasn't. In fact, if anything, the lower fan speed resulted in several (slightly) lower temperatures... presumably because the slower air speed allowed more stagnant air to mix into the exhaust. So I'm pretty comfortable with my setup and I suspect that if an Apple engineer owned my exact iMac, he'd be fine with the lower fan speed too.

 

[nigel415674]

I have a 10 core i9, 64GB memory, 5500XT.

I typically have several apps open, including Chrome with a dozen windows photoshop with a dozen windows, FTP, BBEdit. Im also currently re-endoding my Plex video library to HEVC. I occasionally hear the fans kick up on the machine, but its not constant. Much less than my 2015 iMac i7 4.0 4-core machine. That machine had a fusion drive.

So, the fans go on but to me they're not a problem considering the power of this new machine.

 

[CL14715]

I know what @motrek is talking about. I have my 2020 iMac in a quiet room and I can hear the subtle hum from the machine. I find if I don't focus on it though that I don't notice it anymore. I think I have seen that people have been able to lower defaults to 1000 rpm which yielded "dead silence" and no damage to the machine. It changes after reboot though back to the default 1180-1220 rpm.

 

[PBG4 Dude]

I think it boils down to the pleasant to the ear quality of the whirr sound and thus the build quality of the fans built into the new iMac 2020. Both are not looking good, I gather from everybody here.

I cannot hear the iMac fans at idle speed from where I sit in front of my iMac. I used the noise app on my watch and it measured 32dB at where I sit, and 38dB when placed directly in front of the thermal exhaust port (2cm wide) on my iMac.

If I open the window for fresh air then I don’t hear the fans at all unless they’re at 100%. Maybe if I live in an anechoic chamber I’d feel differently about those 6dB of added noise.

 

[motrek]

I cannot hear the iMac fans at idle speed from where I sit in front of my iMac. I used the noise app on my watch and it measured 32dB at where I sit, and 38dB when placed directly in front of the thermal exhaust port (2cm wide) on my iMac.

If I open the window for fresh air then I don’t hear the fans at all unless they’re at 100%. Maybe if I live in an anechoic chamber I’d feel differently about those 6dB of added noise.

I've used a decibel meter app on my phone to try to measure this too. It annoyed me that it registered basically no difference with the iMac on or off when I could clearly hear a difference.

Several months ago I ran across an article about microphones online that pointed out that the noise floor of the microphones in cell phones (and presumably smartwatches) is usually in the low 30s.

So I don't think we can draw any useful conclusions from these devices and apps that are physically unable to measure quiet sounds in quiet environments.

 

[PBG4 Dude]

I've used a decibel meter app on my phone to try to measure this too. It annoyed me that it registered basically no difference with the iMac on or off when I could clearly hear a difference.

Several months ago I ran across an article about microphones online that pointed out that the noise floor of the microphones in cell phones (and presumably smartwatches) is usually in the low 30s.

So I don't think we can draw any useful conclusions from these devices and apps that are physically unable to measure quiet sounds in quiet environments.

I was more concerned with the rate of change rather than is it exactly 32 or 38 dB. A change of 6dB was registered and I think that’s the more important factor.

 

[motrek]

I was more concerned with the rate of change rather than is it exactly 32 or 38 dB. A change of 6dB was registered and I think that’s the more important factor.

I guess I'm not completely understanding why you're measuring how much noise it's making at the exhaust port behind the computer. That's not where your ears are when you're using the computer. (Or anybody else's ears, presumably.)

I think it's much more interesting to measure how much noise the computer makes, at the user's head position, when the computer is on vs. off.

 

[Lankyman]

It is not my opinion, its a fact. The spinning mechanism inside is making noise. (Do you know how traditional HDD work?)
Unless you were talking about the other part. Regardless, FD is (as we say around here) - For Fusion Sake. FD is a crap product all around. Its prone to failure, its slow and it is limiting in many ways. The fact that you defend it tells me that your usage is not very demanding and you value storage space over everything else.
Regardless, FD is dead and we are very happy about it. One of the worst things from Apple for iMac.
Maybe one day you will see

I’ve already alluded to the fact that since I retired my usage is only light. I say again that despite owning a full SSD iMac as well the FD iMac suits my needs to perfection. I don’t want to use an external drive for storage and a large capacity SSD is to expensive for my needs. As far as my hearing goes it is ‘silent to me’.

 

[petsk]

There's zero doubt that the Fusion Drive is making a lot of noice. One can easily hear this if you use an external SSD as boot drive. When the internal HDD spinns down (if 'put hard disks to sleep when possible' is turned on) it becomes very obvious just how much noice the HDD is making.

 

[filmak]

There's zero doubt that the Fusion Drive is making a lot of noice. One can easily hear this if you use an external SSD as boot drive. When the internal HDD spinns down (if 'put hard disks to sleep when possible' is turned on) it becomes very obvious just how much noice the HDD is making.

Once upon a time there were also problems with its vibrations, so there was also extra noise...

 

[Azrael9]

In my experience it goes like this (from completely silent to noisiest at idle): 2017 21.5" < iMP << 2017 27" <= 2019 27"

Basically the iMP Pro stays at idle noise level even under load. The 27" models get noisy under load, worst of them being the 27" 2017 i7.

You can see the 2017 i7 model in action here:

Running Cinebench for a few seconds already makes it go full blast. It's acutally hilarious how noisy this machine is. Problem with that one is that it can also happen doing light tasks, like using Skype oder reopening a bunch of tabs in your browser.

About that 'fan' noise coming on for even 'light' tasks.

I have ZBrush and the fan noise happens even for browsing the 'Light Box' (project folder browsing...) and it's very distracting.

My 2012 iMac never did this.

I've logged a support ticket with ZBrush/Pixelogic to investigate further.

Azrael.

 

[Azrael9]

I started experiencing kernel panics and forced reboots on my 2020 27" iMac today. Unfortunately, I don't believe your replacement will solve the issue because there seems to be some fundamental flaws with this new iMac. I would suspect it's related to the thermal management system being insufficient for these incredibly hot 10th Gen Intel Core CPUs, but I don't particularly have the patience to continue to investigate this.

I'll be packing my iMac up and returning it to Apple. I'm picking out components now for a PC build for video editing and rendering that won't be getting even remotely close to 100º C, like this iMac seems to enjoy doing.

See my post re: ZBrush.

It seems the thermal management system is not good enough for the Intel CPU.

The temperature seems to flail widely under little provocation.

Azrael.

 

[Azrael9]

Is anyone with the Tier 1 model doing any form of 3D modelling and rendering and hearing the same level of fan engagement?

Azrael.

 

[Azrael9]

I'm loving this thread, it's more entertaining than TV. I have a radical solution - stop listening and start using.

Yes. Ofc. If you wear ear defenders whilst browsing an interface.

Hard to use a computer with your index fingers in each ear.

Azrael.

 

[Lankyman]

There's zero doubt that the Fusion Drive is making a lot of noice. One can easily hear this if you use an external SSD as boot drive. When the internal HDD spinns down (if 'put hard disks to sleep when possible' is turned on) it becomes very obvious just how much noice the HDD is making.

Quantify a lot of noise? I consider a pneumatic drill on a building site a lot of noise.

 

[Azrael9]

I'm going to try running Z-Brush on Windows 10 to compare.

My support question got an answer from Pixologic.

Enabling [Preferenceserformance:Reduce Mac Fan Activity]

and...

disabling [Preferenceserformance:Optimal] then Setting the [Preferenceserformance:MaxThreads] to one less than the maximum available on their system

Deactives multidraw when not sculpting to stop the Mac fan from running constantly. (Tool tips says...in the app.). It's pretty embarrassing when an App has to have a button for that.

The noisy fan bursting in for inconsequential stuff has now disappeared.

It was hyper irritating. A low poly dog and the fan was going off on one.

It might well be down to the hyper threading and turbo behaviour. (I have the app to monitor that...but the app gives no indication that turbo boost has been turned off. I wish Apple would give users the choice to run a 10 core machine at a much lower clock. So we could get the spread of work advantage...but there's no point for the fan to be in hair dryer mode. You're just running the machine at the limit. And how long will an iMac stand that level of heat before it fries in its juices?)

I'm unimpressed with the thermal measures Apple took with this machine. Matt screen? I wish they'd bothered to put proper cooling in. A bit of under volt trickery. Lower clocks. But I don't understand ramming cpus to high clocks only to cut them down moments later as the fan kicks in. It's very distracting from what is a quietly poised machine. What's the point. Burst performance? For how long it lasts? Why bother?

Azrael.

 

[motrek]

...
Deactives multidraw when not sculpting to stop the Mac fan from running constantly. (Tool tips says...in the app.). It's pretty embarrassing when an App has to have a button for that.

If the app is using 100% CPU when not doing anything ("when not sculpting"?) then its multithreading system does seem to be very poorly designed.

...
I'm unimpressed with the thermal measures Apple took with this machine. Matt screen? I wish they'd bothered to put proper cooling in. A bit of under volt trickery. Lower clocks. But I don't understand ramming cpus to high clocks only to cut them down moments later as the fan kicks in. It's very distracting from what is a quietly poised machine. What's the point. Burst performance? For how long it lasts? Why bother?

CPUs and computers in general are almost always designed to compute as fast as possible. Maximum burst speed and maximum sustained speed, temperature allowing. Apple puts expensive CPUs in its iMacs to deliver top performance, not so that they can be undervolted and downclocked. It's no big mystery why an iMac's CPU is configured to deliver maximum performance... imagine what a scandal it would be if it wasn't.

That being said, I agree that it would be nice for the OS to have a feature to limit CPU performance. Maybe a slider that you could drag between "minimum fan noise" and "maximum performance."

(I'm curious... how much is your CPU's clock speed slowing down during sustained use? I find that my iMac's CPU can sustain its maximum all-core boost clock speed indefinitely, but I basically never tax the GPU, so I probably have some thermal headroom with the cooling.)

Ultimately, though, the problem is that Apple puts some pretty high-power components in a small form factor with a cooling system that's not much better than a laptop's. Regardless of how it's advertised, the iMac is not a great choice for people who want great performance.

People who want good performance with good thermals and low fan noise (and expandability) have been underserved by Apple's product lineup ever since the trash can Mac Pro was released. The original Mac Pro was released in 2006 and the base model had a price of $2200... which is ~$2900 adjusted for inflation. An expensive computer, to be sure, but still vastly cheaper than the base model iMac Pro or Mac Pro today. Disappointing.

 

[Azrael9]

Ultimately, though, the problem is that Apple puts some pretty high-power components in a small form factor with a cooling system that's not much better than a laptop's. Regardless of how it's advertised, the iMac is not a great choice for people who want great performance.

People who want good performance with good thermals and low fan noise (and expandability) have been underserved by Apple's product lineup ever since the trash can Mac Pro was released. The original Mac Pro was released in 2006 and the base model had a price of $2200... which is ~$2900 adjusted for inflation. An expensive computer, to be sure, but still vastly cheaper than the base model iMac Pro or Mac Pro today. Disappointing.

Amen to that last paragraph. I won't be arguing with it.

The iMac is probably great for 2D, general production and video work. And music ofc.

The 3D performance is finally here. The 'so last year' and mid-range 5700XT is low clocked not to kick up a fuss and performs 'great for an iMac.'

The cpu. Just. Ugh. What was Apple thinking putting in a 10 core without the iMac Pro's cooling? It's...*face palms.

To be fair. It's not Z-Brush for Mac that doesn't seem optimised but 3D in general. When you have a 'button' that stops the Mac fans from kicking up a fuss all the time in your app. It kind of tells us the state of play.

It seems Windows and Nv's Cuda have stolen a march on Mac in this area. You can see it in gaming and creative apps.

It's like the Mac gets mediocre ports. LW3D, Poser and Z-Brush are all running on this deprecated out of date stale API. I daren't guess how bad they are compared to the windows versions. But I'm going to try running them in Bootcamp. Just to see.

Running on an ancient Open GL. They tend to feel somewhat kludgy rather than buttery smooth.

Nothing can cripple hardware more than poor software efficiency or inefficient thermals. It's a toxic combination.

In short, I agree with your closing two paragraphs the most. Underserved. That's the word. I'd have gone in for the Mac Pro at £2999 with a decent spec. And that's not cheap. Not what I'd class as 'affordable.' Apple's boutique pricing got worse when I didn't even think it could.

The performance is there but the iMac's quiet poise is train wrecked by anything involving a 3D render. Yet 3D gaming on the 5700XT doesn't seem too bad at all. Never hear the fans. But I'm not doing high end gaming. WoW wasn't taxed in QHD or 4k.

But the cpu...if you start doing too much in 3d it belly aches. It seems to be the Achilles heel along with Apple's lazy approach to the cooling on this machine. Compared to the iMac Pro the cooling is backward.

Just makes me think this machine will fry if you push it and it doesn't sound good whilst you're doing a render in 3D eg. something taxing like a Blender render. Doesn't inspire confidence.

The Turbo boost 'feature' is, to me? A short path to frying your components.

I have my old iMac turned with it's back to me. It's giant Aluminium heat sink in a way. All that space. And Apple can't be bothered to do better cooling? it's not like they didn't already have the answer with the iMac Pro.

Azrael.

 

[motrek]

...
In short, I agree with your closing two paragraphs the most. Underserved. That's the word. I'd have gone in for the Mac Pro at £2999 with a decent spec. And that's not cheap. Not what I'd class as 'affordable.' Apple's boutique pricing got worse when I didn't even think it could.
...

It sounds like you're doing 3-D stuff, which is going to be very UI-focused, so your options are limited. I feel for you.

Personally, when I need to do some serious computing, I have a PC in a different room of my house running Linux. It has a recent 8-core AMD CPU and a recent Nvidia graphics card. It cost less than $1000 and, by the numbers, it looks similar to the base model iMac Pro ($5000) in terms of CPU/GPU compute capability. I use my iMac to remote into this computer... so I'm using it with my nice iMac screen, nice keyboard, nice mouse, etc., and I can't really hear any noise it's making because it's in a different room. I like my setup, and it's obviously much more cost-effective than any Apple "Pro" computer, but I imagine it wouldn't be suitable for most tasks.

 

[Azrael9]

It sounds like you're doing 3-D stuff, which is going to be very UI-focused, so your options are limited. I feel for you.

Personally, when I need to do some serious computing, I have a PC in a different room of my house running Linux. It has a recent 8-core AMD CPU and a recent Nvidia graphics card. It cost less than $1000 and, by the numbers, it looks similar to the base model iMac Pro ($5000) in terms of CPU/GPU compute capability. I use my iMac to remote into this computer... so I'm using it with my nice iMac screen, nice keyboard, nice mouse, etc., and I can't really hear any noise it's making because it's in a different room. I like my setup, and it's obviously much more cost-effective than any Apple "Pro" computer, but I imagine it wouldn't be suitable for most tasks.

Hello Motrek.

It's nice to get a couple of replies from someone who 'gets it.'

If I'm modelling in Z-Brush. That's ok. But as soon as you try to render...the fan (I won't use the plural...) kicks in. I've reduced the threads and pressed the 'fan not coming on all the time button' and I can now rotate an 8k polygon Dog.

Pyrrhic victory and all that. And that's what this iMac feels like. The 3D performance is is finally there. And for most things you won't hear the 'fan' it's just ironic that it finally gets a 10 core and it's Intel's 'finest' thermal monster...and all that goes with it IF you're doing 3D renders.

Most of the time you don't hear anything for 'most' tasks if I'm to be fair.

I take your point about your work set up.

A better performing computer could have been had for much less (5k display not withstanding...)

3080 Nv GPU based computer towers are going for less than £2k already with 12 cores.

So you're doing virtualisation to run your PC?

Gawd. I miss the days of blue and white G3 towers for £1300-ish quid.

I'll be adding to the iMac set up with a PC workstation in due course. As was my original intention.

Azrael.

 

[motrek]

...
So you're doing virtualisation to run your PC?
...

I don't know if virtualization is the right word, since it doesn't have to do with virtual machines, but I use the machine remotely via software called "NoMachine." This is the best software I've found to use a computer remotely. Instead of trying to copy bitmaps or graphics instructions from A to B, it encodes the target computer's screen as video, so it can be very responsive (30+ FPS) at the expense of some image quality. Depending on what you're doing, and if both machines are connected to the same local network, you might forget that you're using a different machine.

For things where a lot of the screen contents are changing quickly (e.g., 3-D modeling or video editing) or for things where you need optimal image quality (photo or video editing), I don't think such a setup would be suitable, but that's not the sort of work I do and I haven't tried it, so who knows.