Recent 27" iMacs are NOT silent

Michael Scrip

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Recent 27" iMacs are NOT silent
I'm confused... did Apple advertise the iMac as a silent computer?

I take the word "silent" to mean "no noise whatsoever"

But this thing has a fan inside! A moving part! Air velocity and whatnot.

So I don't know what you were expecting.

The only "silent" computers are passively-cooled where the case is basically a giant heat sink.

 

motrek

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I don't think you are crazy either, but maybe not being realistic.

If you want something silent, you can always get an iPad Pro, but this comes back to trade offs again.
...
I don't know if you're mocking me with the iPad Pro suggestion. I need a real computer, running MacOS.

It's not impossible to have a Mac setup that's basically silent. The Mac Mini makes a small amount of noise, but it can be relocated. When I put my old Mac Mini on the outside edge of my desk, on the floor, I can not hear it. I would be surprised if anybody could.

If you want a Mac setup that's literally silent, that's doable too. My 2015 MacBook Pro is semi-passively cooled. When it's idle, or close to idle, the fan is literally not spinning.

So it's not like what I'm wishing for is unreasonable or not realistic or not solvable. The only tricky bit is getting a Mac to quietly drive a 4K monitor in HiDPI mode, really. But it's not like 1440p monitors are unusable. Not as nice, but not unusable.

Getting a new Mac Mini with a nice display would probably help with the noise, but if you want the performance, then you are probably going to need an eGPU, which might make some noise.
I don't really do anything graphically intensive so I don't really care about GPU performance. As for CPU performance, the 2015 iMac that I bought isn't really meaningfully faster than the base-model Mac Mini these days.
- - Post merged: - -

I'm confused... did Apple advertise the iMac as a silent computer?

I take the word "silent" to mean "no noise whatsoever"

But this thing has a fan inside! A moving part! Air velocity and whatnot.

So I don't know what you were expecting.
There are a lot of people who claim that iMacs are silent when idle. A lot of people on this thread, even. As I mentioned in my first post, I wanted to create a thread to counterbalance that sort of misinformation.

Also, I didn't expect the iMac to be literally silent. I knew it had a fan. The only question was, would I be able to hear it or not. It's possible that I would not have been able to hear it. I had a MacBook Air for years and it had a fan that was constantly spinning at 1200 RPM and I couldn't hear it. But the iMac is much louder.

The only "silent" computers are passively-cooled where the case is basically a giant heat sink.
Nitpick: there are also semi-passively cooled computers where none of the fans spin unless temperatures necessitate it. It's actually pretty easy to build a PC that's literally silent under most conditions.
 
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vertical smile

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I don't know if you're mocking me with the iPad Pro suggestion. I need a real computer, running MacOS.
I am not mocking you at all, just pointing out the trade offs of having a completely silent device versus one that is not as quiet.

My 2015 MacBook Pro is semi-passively cooled. When it's idle, or close to idle, the fan is literally not spinning.
Why not use this then?

But it's not like 1440p monitors are unusable. Not as nice, but not unusable.
This is priorities and trade offs again.

The Mac Mini makes a small amount of noise, but it can be relocated. When I put my old Mac Mini on the outside edge of my desk, on the floor, I can not hear it.
This set up sounds like a more ideal solution for you with your priorities. Maybe you should consider returning the iMac for a Mac Mini.
 

Lankyman

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How exactly does increasing ambient noise help in reducing overall noise levels to create a dead-silent work environment?
It doesn’t it simply masks any perceived noise from the iMac. You can then fixate on the NAS if that is your want.
 

motrek

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This set up sounds like a more ideal solution for you with your priorities. Maybe you should consider returning the iMac for a Mac Mini.
Right. I think I said I was considering that in an earlier post?

I bought the 2015 iMac used via Craigslist. Yesterday, I listed it for sale on Craigslist. If somebody wants to buy it, fine. I will sell it to them and sort out something else. Probably I'll just go back to using my Mac Mini for a while since I still have it. The net result is that I will have essentially rented a nice iMac and used it for a while, which is not a bad thing. I have been thinking about switching to an iMac, off and on, for the past 2-3 years but I was worried that the fan noise would bother me. Basically I have learned the answer to that question (it does) and I can stop thinking about switching to an iMac.

So, this is not a bad situation, per se, for anybody.

Although I will continue to be annoyed with Apple's strategy of combining their higher-end computer with their higher-end display. If I could separate the computer part of the iMac from the display part, then I could put the computer part down on the floor where I had my Mac Mini, maybe put some acoustic treatment around the corner, and I suspect I would be pretty happy with that setup. But no, that's not the Apple Way anymore.
 

motrek

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Dont expect too much about the cooling system on iMac with 8 years old cooling design.
Actually, quick update. I drummed up the courage to try this:


Using the suggested software and terminal commands, I lowered the minimum fan speed from 1200 RPM to 1000 RPM. This made an enormous difference. Right now it's the middle of the day, so there's somewhat more ambient noise in my office than at night, but I can no longer hear my iMac. Very satisfying.

I compared all of my system temperatures (via Macs Fan Control) at 1000 RPM and 1200 RPM and there's basically no difference. If anything, the temperatures at 1000 RPM seem to be a tiny bit cooler. So there's no concern that the lower fan speed is bad for the computer at idle. (Not that running a few degrees warmer would be bad for the computer anyway... I'm sure it's engineered to run under load indefinitely.)

I have configured Macs Fan Control to control the fan speed according to the CPU PECI temperature. The fan begins to ramp up at 60C and reaches its maximum speed at 90C. I did a couple of quick tests and this turns out to be much more aggressive than Apple's fan speed control algorithm. The only concern here is that the fan speed is based on only one temperature reading (out of ~20 total) so I wonder if there's a situation where something might be overheating but the CPU temperature stays under 60C. That would be pretty bad, but such a scenario seems unlikely to me.

I have no idea why Apple specified the minimum fan speed to be 1200 RPM in the first place. The only function of those extra 200 RPM seems to be to make noise. I suppose it would be too much to hope for that Apple might lower the speed themselves with a firmware update in the future.
 

_Skyfire_

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Aug 16, 2017
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Actually, quick update. I drummed up the courage to try this:


Using the suggested software and terminal commands, I lowered the minimum fan speed from 1200 RPM to 1000 RPM. This made an enormous difference. Right now it's the middle of the day, so there's somewhat more ambient noise in my office than at night, but I can no longer hear my iMac. Very satisfying.

I compared all of my system temperatures (via Macs Fan Control) at 1000 RPM and 1200 RPM and there's basically no difference. If anything, the temperatures at 1000 RPM seem to be a tiny bit cooler. So there's no concern that the lower fan speed is bad for the computer at idle. (Not that running a few degrees warmer would be bad for the computer anyway... I'm sure it's engineered to run under load indefinitely.)

I have configured Macs Fan Control to control the fan speed according to the CPU PECI temperature. The fan begins to ramp up at 60C and reaches its maximum speed at 90C. I did a couple of quick tests and this turns out to be much more aggressive than Apple's fan speed control algorithm. The only concern here is that the fan speed is based on only one temperature reading (out of ~20 total) so I wonder if there's a situation where something might be overheating but the CPU temperature stays under 60C. That would be pretty bad, but such a scenario seems unlikely to me.

I have no idea why Apple specified the minimum fan speed to be 1200 RPM in the first place. The only function of those extra 200 RPM seems to be to make noise. I suppose it would be too much to hope for that Apple might lower the speed themselves with a firmware update in the future.
Good for you, fyi macrumors also has a thread on the topic. And to allay those fears, just use ambient temp as the value for MFC
 

motrek

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Good for you, fyi macrumors also has a thread on the topic. And to allay those fears, just use ambient temp as the value for MFC
Looking at the ambient temp values, they seem to try to indicate the ambient temperature of the room, and not the internal electronics. I can load my CPU and get the temperatures into the 90s but the ambient temperature reading never changes and is stuck at 21, which seems like the temperature of the room.

CPU PECI seems to show the overall CPU temperature, not the temperature of particular cores, so that seems like a good thing to trigger off of.

Since the CPU and the GPU are really the only two components of the computer that can produce a significant amount of heat, I think there's a small concern that the GPU might get loaded and hot but the fan won't spin up because it's triggered off of the CPU. But I'm not too worried about that because 1) the GPU should throttle if it gets too hot, and 2) these things are connected to each other by the same heatsink, so I don't think the GPU can get hot without the CPU also getting hot. (I can definitely see the GPU temperatures go up if I stress the CPU...)

Just found out that when the computer wakes from sleep, the SMC fan control values are reset to factory defaults. Boo.
 

Lankyman

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I have to smile when I see someone write 'ramp up'. I have yet to make my 2019 27inch FD iMac break sweat never mind 'ramp up'. For me this is a totally quiet iMac - just purr....fect. 😀
 
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petsk

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I find my MBP 16" noisier than my iMac 27" late 2015 with 2TB fusion drive, both when idle and under load.
 

chrono1081

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It blows my mind that in 2020 people think their computer should be silent. Can it be nearly silent on some tasks? Sure, but most people are surfing the web (which thanks to all the crap added to web pages, can be taxing depending on the page), or use Youtube (video is taxing). Computers need to keep themselves cool when they perform tasks that will cause them to work harder and to do this the fans kick on. Without them your chip will heat up to the point it'll shut itself off, but before it does that all your stuffwill stutter and lag.

Expecting a computer to be silent is just silly and unrealistic.
 

smirking

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The only "silent" computers are passively-cooled where the case is basically a giant heat sink.
Even those aren't truly silent though. Memory, processors, and SSDs can all make noise. My 2018 MBP makes noise whenever I move the mouse when it's powering my LG 5K. It's not loud, but I almost wish it were. It's just loud enough to make me wonder if I was imagining things.
 

motrek

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It blows my mind that in 2020 people think their computer should be silent. Can it be nearly silent on some tasks? Sure, but most people are surfing the web (which thanks to all the crap added to web pages, can be taxing depending on the page), or use Youtube (video is taxing). Computers need to keep themselves cool when they perform tasks that will cause them to work harder and to do this the fans kick on. Without them your chip will heat up to the point it'll shut itself off, but before it does that all your stuffwill stutter and lag.

Expecting a computer to be silent is just silly and unrealistic.
Nonsense. You're exactly wrong. Modern CPUs use an astonishingly small amount of power when they're not being taxed. (And no, web browsing and playing YouTube videos is not taxing to any computer made in the last 10 years. Check Activity Monitor.)

Apple made the 2015 MacBook which was completely passively cooled with a teensy little heatsink. People can use that computer for basic tasks all day long and it works great. Web browsing, YouTube, etc. etc. Sure, if you max out the CPU for 30+ seconds, it will start to throttle. Meaning that it will run somewhat slower, but it will still be perfectly usable. It will not "shut itself off" as you say.

My 2015 MacBook Pro is semi-passively cooled. The fan is literally stopped almost the entire time I'm using it to do anything. I have to run one of the CPU cores at 100% for about 15 seconds before the fan even turns on. This happens to me very rarely.

So it is absolutely 100% possible for Apple to make a computer that's literally silent, since they've already done so. And it's 100% possible for them to make a computer that's usually silent, i.e., semi-passively cooled, since they've already done so. So I don't think it's unreasonable at all to expect all their computers to be silent when doing light-duty work.

The logic board in a 2015 MacBook is about the size of an iPhone 6, and only a couple millimeters thick. Imagine that as the basis of a hypothetical silent iMac. To drive the 5K display you'd probably want a discrete GPU, though, so maybe double the size of the hypothetical logic board. Add a nice heatsink (really, anything would be nice compared to a 2015 MacBook's heatsink) and some vertically-oriented vents and it would probably never throttle. The internal power supply could be much smaller since it wouldn't have to support a desktop CPU. The whole thing could be the size of a typical 27" monitor that you might see at Best Buy, i.e., it wouldn't need the huge bezels that current iMacs have.

iMac Air, anyone?
- - Post merged: - -

Even those aren't truly silent though. Memory, processors, and SSDs can all make noise. My 2018 MBP makes noise whenever I move the mouse when it's powering my LG 5K. It's not loud, but I almost wish it were. It's just loud enough to make me wonder if I was imagining things.
Well, alternating current will generate a magnetic field which can cause nearby metal things to vibrate. The things themselves might make a noise because they're vibrating, or they might vibrate against something and the contact might make a noise. This is often called coil whine. If a system is designed and built in such a way that it doesn't have metal bits that can vibrate, then it shouldn't make any noise at all. I don't think I've ever heard any of my Apple computers make coil whine noises.

So I suspect the noise you're hearing is from the monitor doing whatever electronic things it needs to do to change the image (move the cursor) and not from the MacBook itself.

What can also happen is, depending on your audio setup, electronic activity could induce a signal on the input to your speakers and your speakers will make a corresponding noise. This will happen when your audio electronics, speaker cables, and/or speakers are poorly shielded. I'm sure we probably all remember when computer speakers would make noise when you received a call on your cell phone:

 
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smirking

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So I suspect the noise you're hearing is from the monitor doing whatever electronic things it needs to do to change the image (move the cursor) and not from the MacBook itself.
It's definitely coming from my MBP. I had a 2016 and now a 2018. My 2016 was silent or nearly silent. I only started noticing this when I upgraded to a 2018. I suspect it's mostly coming from the GPU because things that tax the GPU seem more likely to create high pitched whirring noises.

It also makes some of these noises when disconnected from my 5K monitor. It's just easiest to reproduce when connected because using an external USB mouse is all that it takes. On the other hand, a Bluetooth trackpad doesn't produce the same result.
 

motrek

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It's definitely coming from my MBP. I had a 2016 and now a 2018. My 2016 was silent or nearly silent. I only started noticing this when I upgraded to a 2018. I suspect it's mostly coming from the GPU because things that tax the GPU seem more likely to create high pitched whirring noises.

It also makes some of these noises when disconnected from my 5K monitor. It's just easiest to reproduce when connected because using an external USB mouse is all that it takes. On the other hand, a Bluetooth trackpad doesn't produce the same result.
Are you sure it's from the electronics and not just from the/a fan ramping up for a sec?
 

mikehalloran

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A silent MacBook Pro? Where do I sign up?

My MBP fan spins up at random even when I've not touched it for a few hours. It gets so loud at times, I can hear it over the drugs, something that never happens on the iMP unless I'm testing the fans in TechTool Pro.

I'm serious, BTW. Tinnitus from the drugs I take to stay alive is my constant companion, unfortunately. When producing or mastering audio, I need to hear through it, something I learned to do about a decade ago.
 

motrek

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A silent MacBook Pro? Where do I sign up?

My MBP fan spins up at random even when I've not touched it for a few hours. It gets so loud at times, I can hear it over the drugs, something that never happens on the iMP unless I'm testing the fans in TechTool Pro.

I'm serious, BTW. Tinnitus from the drugs I take to stay alive is my constant companion, unfortunately. When producing or mastering audio, I need to hear through it, something I learned to do about a decade ago.
Well, the 2015 MacBook is silent, but it's not a MacBook Pro. Not sure it would have the performance you're looking for, although I'm sure it's plenty fast for most things.

Your MBP fans aren't spinning up "at random." There might not be an obvious reason, but there's always a reason. Next time it happens, check Activity Monitor and see what's stressing your CPU.

I had a problem a while ago where my fans also seemed to spin up "at random." Turns out it was due to some poorly-engineered ads that were being displayed on a web site that I frequent. I installed an ad blocker and the problem disappeared. As much as I would like to support web sites via ad revenue, there's a limit to how much electricity and CPU power I'm willing to give these people for the privilege of looking at their dumb ads.
 
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smirking

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Are you sure it's from the electronics and not just from the/a fan ramping up for a sec?
Yeah. I don't know of any fan that sounds like that and I can also get it to last much longer than a sec at the exact same pitch and volume... just keep moving the mouse.
 

motrek

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Yeah. I don't know of any fan that sounds like that and I can also get it to last much longer than a sec at the exact same pitch and volume... just keep moving the mouse.
Huh. Well, that's a shame. I don't know if that completely rules out a fan... at a certain lower RPM, my MBP fan has a resonance or it's unbalanced or something and it'll make a weird high-pitched noise. Pretty annoying, but the fan rarely runs at that speed. (Actually it rarely spins at all, with how I use the computer.) But yeah, could be capacitor/coil whine.
 

smirking

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Huh. Well, that's a shame. I don't know if that completely rules out a fan...
It's unlikely, but I'll entertain the idea that it could still be a fan. Even if it were, it'd still be an electrical noise instead of a mechanical one.

Other people here have reported electrical noises with their MBPs that only happen upon certain events like anytime there's a SSD write. I get that too. If I'm restoring a 4GB MySQL db to one of my VMs, I hear my MBP buzzing with activity. It's also a slightly different pitch than the noise I get from moving the mouse.

I'm not freaking out about either noise. I wish my 2018 were as quiet as my 2016, but it is what it is and usually doesn't bother me. When it does, I just put on music to drown it out. It's barely audible and could be more widespread than reported because the pitch of the sound is high enough that lots of people my age may not be able to hear it.

Electricity isn't silent so you can't expect anything powered by electricity to be totally silent. Sometimes, I really enjoy it when the power goes out. You suddenly realize how much background noise you're tuning out on a day in and day out basis.
 
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motrek

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It's unlikely, but I'll entertain the idea that it could still be a fan. Even if it were, it'd still be an electrical noise instead of a mechanical one.

Other people here have reported electrical noises with their MBPs that only happen upon certain events like anytime there's a SSD write. I get that too. If I'm restoring a 4GB MySQL db to one of my VMs, I hear my MBP buzzing with activity. It's also a slightly different pitch than the noise I get from moving the mouse.

I'm not freaking out about either noise. I wish my 2018 were as quiet as my 2016, but it is what it is and usually doesn't bother me. When it does, I just put on music to drown it out. It's barely audible and could be more widespread than reported because the pitch of the sound is high enough that lots of people my age may not be able to hear it.

Electricity isn't silent so you can't expect anything powered by electricity to be totally silent. Sometimes, I really enjoy it when the power goes out. You suddenly realize how much background noise you're tuning out on a day in and day out basis.
Well, I assume you know this, but electricity itself is silent, i.e., the movement of electrons between atoms/molecules. Something has to be creating waves of air pressure for it to make noise. (That's the definition of sound, after all.)

Like I said in a post above, alternating current can generate magnetic fields that cause metal things to move and vibrate and make sound. And things that use electricity will often convert it to heat in one way or the other, which can cause thermal expansion (and then contraction later) which can make noise/noises. But if none of that is going on then electricity will be silent.

MBP manufacturing tolerances are probably such that some buzzy/noisy models can escape.
 
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smirking

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Well, I assume you know this, but electricity itself is silent, i.e., the movement of electrons between atoms/molecules. Something has to be creating waves of air pressure for it to make noise. (That's the definition of sound, after all.)
Nope. Didn't know that so thank you for that. I'm not a electrical engineer nor a physicist so I don't have the insight to separate electromagnetic induced sources of sound from just the power itself.
 

chrono1081

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Nonsense. You're exactly wrong.
I'm actually not, there's literally nothing you can say to make what I said incorrect. Fans cool the CPU and fans make noise. It's physics.

You're just desperate to be angry about something so I'm going to end our conversation.