The new iMac is a lot noisier!

[solarflab]

Here is a oneliner for stress testing the cpu via the yes command. Paste this in a terminal.

for i in {1..$(seq $(sysctl -n hw.ncpu))}; do yes > /dev/null & done
​

Explanation: Start the same number of yes instances as there are logical cores.


Stop stress test with command

killall yes​

 

[whatevs]

Here is a oneliner for stress testing the cpu via the yes command. Paste this in a terminal.

for i in {1..$(seq $(sysctl -n hw.ncpu))}; do yes > /dev/null & done
​

Explanation: Start the same number of yes instances as there are logical cores.


Stop stress test with command

killall yes​

thanks for sharing. tested on my i5 3.8 w/580 for around 10-15min... CPU temps went to low 90s C, but fan did NOT move significantly from 1200 rpm.

EDIT: fan did NOT move

 

[johannnn]

thanks for sharing. tested on my i5 3.8 w/580 for around 10-15min... CPU temps went to low 90s C, but fan did move significantly from 1200 rpm.

What's your setup? Do you have any fan control app? My iMac for sure starts making a lot of noise if the CPU reaches 90C

 

[whatevs]

What's your setup? Do you have any fan control app? My iMac for sure starts making a lot of noise if the CPU reaches 90C

I have iStat Menus installed for monitoring but I do not use any fan control app.

I haven't tried gaming yet, but so far I can not move the fan any faster than about 1200 rpm.

 

[josduc]

Just tried the stress test for 15 minuten and my cpu won't get hotter than 55 degrees celsius. Fan didn't get beyond 1200 rpm. So it stays nice and cool.

When it's really quiet in the house I can hear the fan at idle but I guess it's just by design. Sound like air rushing through the case. Maybe the sound is also amplified because the iMac is boxed in between a wall, two speakers and off course the desk.

I will not return it because of this because it seems I hit the jackpot with the screen. Good uniformity and no noticeable backlight bleed.

Maybe the fan needs breaking in?

I have the i5@ 3,8 GHz and 580 graphics.

 

[SaSaSushi]

As expected, on my i7 4.2GHz the fan ramps up to the max of 2700rpm within about one minute of starting the stress test.

However, the CPU core temps stay steady at around 90-92°C and even considering the CPU proximity sensor right next to it might be slow to react to high core temps after 15 minutes it never goes over 61°C.

I'm glad the fan's working.

In my regular usage after 2 months with the i7 the fan is at 1200rpm idle about 99.9% of the time. YMMV.

 

[dsc888]

I just performed the "yes" command test in terminal and am quite impressed with my results. To start, I'm one of those who returned my i7 for an i5 after getting annoyed at the fan noise that would occur as I scrolled though Apples Photos app and while doing the same in Adobe Lightroom while checking out previews of my RAW files after I imported my files.

My setup is now a i5 7600K 3.8/32 Gb RAM/1 Tb SSD/580 PRO. And here's what I got after running the load test for 20 minutes in a 73 degree F (22.7 degree C) air conditioned room...

>Highest temps I managed to get under both iStat and Intel Power Gadget was 84 degrees C.
>Fan Speeds varied from 1192 to 1207 RPMs.
>CPU turbod to 4.0 Ghz and stayed there under the Intel app.
>Rear Exhaust was mildly warm at the back of the iMac.
>Rear aluminum chassis was slightly warm to the touch in the center below the air exhaust.
>Fan noise was identical to idle fan noise (which is audible in a quiet room only normally)

I'm very impressed to say the least. After reading this thread and considering what EugW did, I returned my unit to Apple with no issue and orders the top tier i5 to get the highest spec graphics card. The i7's fans, although not very loud, fired up too eagerly and I wanted a quieter computing experience. So far, I've only been able to get the fans to spin up very mildly to 1400 to 1600 RPMs while attempting to watch an 8K video on YouTube. That's about it. I'm sure there will be other times when it'll happened but I've not come across such tasks yet.

 

[whatevs]

Ran the yes script again for approximately 15min in a room at 76 F (24.4 C). Fan stayed at baseline speeds. CPU temps in mid 80s for my i5 7600k w/580.

here are images for idle and load.

 

[SaSaSushi]

Thanks for reminding me. I forgot to mention the ambient room temperature when I tested my i7 above.

It was just over 30°C in the room at the time.

 

[propower]

Here is a oneliner for stress testing the cpu via the yes command. Paste this in a terminal.

for i in {1..$(seq $(sysctl -n hw.ncpu))}; do yes > /dev/null & done
​

Explanation: Start the same number of yes instances as there are logical cores.


Stop stress test with command

killall yes​

I have used this command from an old OSX Daily post:
http://osxdaily.com/2012/10/02/stress-test-mac-cpu/

yes > /dev/null &

Just repeat paste for as many logical cores as you wish to stress. For audio work I find loading the CPU with YES ~ as much as typical sessions is useful when assessing the threshold of fan noise. Stress all cores if nothing else does it.

Same end task command.

 

[solarflab]

I have used this command from an old OSX Daily post:
http://osxdaily.com/2012/10/02/stress-test-mac-cpu/

yes > /dev/null &

Just repeat paste for as many logical cores as you wish to stress. For audio work I find loading the CPU with YES ~ as much as typical sessions is useful when assessing the threshold of fan noise. Stress all cores if nothing else does it.

Same end task command.

Yes, that works as well. Only difference is that my suggestion stresses all cores at once, no need to copy and paste multiple times.

 

[Simon Young]

I'm on the verge of buying a new 27" iMac and have been following this topic with great interest. I'm a video editor working with Final Cut Pro, Motion, Compressor and Handbrake, so I'm opting for 580 graphics, a 1TB SSD and at least 32GB RAM. But I'm torn over the processor. I like the i7 7700K for its hyperthreading capability, but as someone who does quite a lot of sound mixing for video, I don't really want noisy fans whirring up whenever I'm scrubbing around a big project in FCPX (for example).

However, as someone pointed out a while ago in this thread, the i7's turbo mode can be prevented via a simple app, limiting it to 4.2GHz and preventing the fans from needing to rev up quite so loud. Also it's my understanding that hyperthreading can be turned off via Xcode. This would mean that, in theory, I could leave turbo and hyperthreading off until I need to do a big video encode, resulting in a quieter computer the rest of the time while I'm actually sitting at it to do work.

I have a few questions about this approach, if any kind soul is able to enlighten me:

1) Would turning off turbo and hyperthreading effectively make the i7 behave like an i5 7600K, and would that mean the fans would behave similarly to how they do with the i5? Or does the i7 still get hotter than the i5 at 4.2GHz, meaning the fans are still more noticeable even with those functions restricted?

2) Is there any potential danger or risk in using a 3rd party app to disable processor functions like turbo or hyperthreading? MacOS sees that the processor is an i7 7700K, so I would presume it expects it to behave like one. Therefore might altering its intended functions have some ramifications elsewhere, like confusing the SMC, causing fans to act strangely or something like that? Sounds a bit paranoid but I have never really done anything like suppressing processor functions, so just thought I'd ask!

3) How easy is it to use Xcode to switch off hyperthreading? I've never used Xcode before and don't want it to become a fiddly procedure I regularly have to do just to keep the machine quiet.

Ultimately I'm guessing many of you will suggest I simply get the i5 7600K, enjoy the guarantee of a slightly quieter iMac and don't worry too much about the lower performance on the occasions I need to do encoding or rendering Motion projects. I'm very nearly in agreement with this myself... but a little voice keeps pushing me towards the i7! Money isn't really an issue, only noise. If I can have the best of both worlds (i.e. quieter, slightly slower i5 performance most of the time, and noisier, all guns blazing i7 performance only when I need it) then shouldn't I take that option and just put up with the software fiddling?

TL;DR - Does turning off turbo and hyperthreading on the i7 7700K effectively turn it into an i5 7600K, with regards temperature and therefore fan behaviour?

Sorry for the long post, and thanks in advance!

 

[czacha]

If you are going to turn off HT (sic!) then don't buy it .. just get i5.

 

[USAntigoon]

I'm on the verge of buying a new 27" iMac and have been following this topic with great interest. I'm a video editor working with Final Cut Pro, Motion, Compressor and Handbrake, so I'm opting for 580 graphics, a 1TB SSD and at least 32GB RAM. But I'm torn over the processor. I like the i7 7700K for its hyperthreading capability, but as someone who does quite a lot of sound mixing for video, I don't really want noisy fans whirring up whenever I'm scrubbing around a big project in FCPX (for example).

However, as someone pointed out a while ago in this thread, the i7's turbo mode can be prevented via a simple app, limiting it to 4.2GHz and preventing the fans from needing to rev up quite so loud. Also it's my understanding that hyperthreading can be turned off via Xcode. This would mean that, in theory, I could leave turbo and hyperthreading off until I need to do a big video encode, resulting in a quieter computer the rest of the time while I'm actually sitting at it to do work.

I have a few questions about this approach, if any kind soul is able to enlighten me:

1) Would turning off turbo and hyperthreading effectively make the i7 behave like an i5 7600K, and would that mean the fans would behave similarly to how they do with the i5? Or does the i7 still get hotter than the i5 at 4.2GHz, meaning the fans are still more noticeable even with those functions restricted?

2) Is there any potential danger or risk in using a 3rd party app to disable processor functions like turbo or hyperthreading? MacOS sees that the processor is an i7 7700K, so I would presume it expects it to behave like one. Therefore might altering its intended functions have some ramifications elsewhere, like confusing the SMC, causing fans to act strangely or something like that? Sounds a bit paranoid but I have never really done anything like suppressing processor functions, so just thought I'd ask!

3) How easy is it to use Xcode to switch off hyperthreading? I've never used Xcode before and don't want it to become a fiddly procedure I regularly have to do just to keep the machine quiet.

Ultimately I'm guessing many of you will suggest I simply get the i5 7600K, enjoy the guarantee of a slightly quieter iMac and don't worry too much about the lower performance on the occasions I need to do encoding or rendering Motion projects. I'm very nearly in agreement with this myself... but a little voice keeps pushing me towards the i7! Money isn't really an issue, only noise. If I can have the best of both worlds (i.e. quieter, slightly slower i5 performance most of the time, and noisier, all guns blazing i7 performance only when I need it) then shouldn't I take that option and just put up with the software fiddling?

TL;DR - Does turning off turbo and hyperthreading on the i7 7700K effectively turn it into an i5 7600K, with regards temperature and therefore fan behaviour?

Sorry for the long post, and thanks in advance!

I understand your dilemma, got the same concerns as I also do a lot of FCPX video work and Capture One Pro RAW processing..
In the event there is a quality consistency problem with the current fan and cooling system in the i7 environment, some modification "might" become evident and implemented soon.
I am going to wait untill the iMac Pro is launched to do a new re-evaluation. A 20% higher investment for a iMac Pro is indeed something you cannot ignore, but with the features offered in the new iMac Pro it might well be worth investing this additional 20%...
Anyway, a purchase delay till December might be a wise decision ...just my 2cents of input..

 

[EugW]

I understand your dilemma, got the same concerns as I also do a lot of FCPX video work and Capture One Pro RAW processing..
In the event there is a quality consistency problem with the current fan and cooling system in the i7 environment, some modification "might" become evident and implemented soon.
I am going to wait untill the iMac Pro is launched to do a new re-evaluation. A 20% higher investment for a iMac Pro is indeed something you cannot ignore, but with the features offered in the new iMac Pro it might well be worth investing this additional 20%...
Anyway, a purchase delay till December might be a wise decision ...just my 2cents of input..

I’m curious how the iMac Pro will handle HEVC. Some of the rumoured CPU options for the iMac Pro do not support Intel Quick Sync. Hopefully it’s not just software HEVC decode/encode.

 

[Apple_Robert]

Wondering whether I should get i5 or i7. I do a lot of recordings with Screenflow; would be nice if the fan didn't kick on. (Im getting an SSD.) also do quite a bit of photography with LR and PS, so was leaning toward the 4.2 i7.

In my opinion, not wanting the fans to turn on is not the right mindset.

I have the 27" i5 3.8 GHZ 1TB SSD model (with upgraded 40GB RAM). I have been doing a good bit of video transcoding with the new iMac and the fans do turn on during encoding, albeit the noise level is still what I consider low.

I had the 2TB Fusion Drive model previously (for a week) and it was definitely louder during load. Neither of the models are completely silent, even when idle. You have to put your ear down to the back vent to hear what little noise there is when idle.

 

[EugW]

In my opinion, not wanting the fans to turn on is not the right mindset.

I have the 27" i5 3.8 GHZ 1TB SSD model (with upgraded 40GB RAM). I have been doing a good bit of video transcoding with the new iMac and the fans do turn on during encoding, albeit the noise level is still what I consider low.

I had the 2TB Fusion Drive model previously (for a week) and it was definitely louder during load. Neither of the models are completely silent, even when idle. You have to put your ear down to the back vent to hear what little noise there is when idle.

The i7 gets quite loud. Check your fan speed with a third party app. The i7 gets to its max 2700 rpm fairly quickly under sustained load. If it's under around 2000 rpm, it's considerably quieter. At idle it's 1200 rpm.

 

[Apple_Robert]

The i7 gets quite loud. Check your fan speed with a third party app. The i7 gets to its max 2700 rpm fairly quickly under sustained load. If it's under around 2000 rpm, it's considerably quieter. At idle it's 1200 rpm.

Thanks for reply. Is there a fan app that most use around here, that I can test with?

 

[joema2]

I'm on the verge of buying a new 27" iMac...I'm a video editor working with Final Cut Pro, Motion, Compressor and Handbrake, so I'm opting for 580 graphics, a 1TB SSD and at least 32GB RAM. But I'm torn over the processor. I like the i7 7700K for its hyperthreading capability, but as someone who does quite a lot of sound mixing for video, I don't really want noisy fans whirring up whenever I'm scrubbing around a big project in FCPX (for example)....it's my understanding that hyperthreading can be turned off via Xcode....Does turning off turbo and hyperthreading on the i7 7700K effectively turn it into an i5 7600K, with regards temperature and therefore fan behaviour?...

As a professional video editor my desk is covered with Thunderbolt drive arrays so the additional noise of an i7 is somewhat obscured by this. Usually when I'm editing 4k H264 in FCPX the fans don't spin up. However when I transcode to proxy they will spin up, but at that point the machine is bogged down for hours on the transcode, so I can't do anything else anyway.

You don't need Xcode to disable hyperthreading, this little utility called CPUSetter will do it. Use at your own risk, but I've tested it and had no problems: https://www.macupdate.com/app/mac/48580/cpusetter

However I didn't notice a significant change in noise or heat when hyperthreading was disabled on my 2017 iMac i7.

Everyone's workflow and priorities are different but for my work I need the fastest possible machine that will run FCPX. If it was so loud I had to wear ear plugs I'd still take that provided it was 2-3x faster.

If you will be encoding or decoding to or from H264 or H265, I'd recommend FCPX and Compressor over Handbrake which does not support Quick Sync on Mac. H265 (HEVC) will be supported in High Sierra for FCPX and Compressor, but I doubt Handbrake will support that.

 

[propower]

In my testing with the i7, turning off HT accomplished nothing for mitigating thermal rise - really - nothing. Turning Turbo OFF helps a little (4.2GHz). The 3.8 i5 with Turbo ON and all cores maxed out (YES test) (4GHz) will be on the verge of getting the fans up - high 80s for CPU temp. Video encoding with turbo ON will get a bit of fans - maybe 1800 RPM depending on room temp and multiple monitor options. The 3.8 i5 with Turbo OFF (3.8GHz) and max load will hover in the 70s. I concluded that max clock speed is the thing that drives thermals in these units. Max load on the i5 Turbo ON and OFF gave CPU power of 40W/30W. The jump from 3.8 to 4.0 gave a 25% increase in power. I believe the jump from 4.0 to 4.2 is similar if not more. If you need it quiet then light loads on the i7 or the 3.8 with Turbo OFF are the tickets (also the other i5s as well). If you need the power though - the i7 is the fastest and has hyperthreading.

 

[circuitt]

I'm thinking about getting a 21.5 i7 imac. Was wondering if anyone has used it with (Logic,Abelton) and is the fan loud as everyone is saying? I have a project coming up and I track in the same room as my mac so, don't need a bunch of fan noise coming through the mic.

 

[EugW]

I'm thinking about getting a 21.5 i7 imac. Was wondering if anyone has used it with (Logic,Abelton) and is the fan loud as everyone is saying? I have a project coming up and I track in the same room as my mac so, don't need a bunch of fan noise coming through the mic.

The i7 7700 in the 21.5" is a different chip. We don't have many reports of it here but on paper it's considerably lower power than the i7 7700K in the 27". However, the 21.5" is also a smaller form factor.

 

[mpConroe]

Jeez guys, is it really such a big problem for some of you?
I mean, I'm 23. I had a lot of PC's and laptops since 1997, when I got my first computer with Windows 95. iMac is my first all in one desktop. My first MacBook from white plastic was creating more noise than my current iMac. All of my Windows laptops, such as Asus, Sony Vaio, another Asus, make much more noise than iMac.

Browsing a web and youtube with iTunes doesn't affect my ears. Only video rendering or gaming has. But, you know, it's a computer and it can make noise, it's not a MacBook with m3 and no fan! It makes noise cos it gets hot. It's normal. Deal with it and stop panicking. And as I said, it's not THAT BAD like PC laptops.

 

[robeddie]

Jeez guys, is it really such a big problem for some of you?
I mean, I'm 23. I had a lot of PC's and laptops since 1997, when I got my first computer with Windows 95. iMac is my first all in one desktop. My first MacBook from white plastic was creating more noise than my current iMac. All of my Windows laptops, such as Asus, Sony Vaio, another Asus, make much more noise than iMac.

Browsing a web and youtube with iTunes doesn't affect my ears. Only video rendering or gaming has. But, you know, it's a computer and it can make noise, it's not a MacBook with m3 and no fan! It makes noise cos it gets hot. It's normal. Deal with it and stop panicking. And as I said, it's not THAT BAD like PC laptops.

I think you're missing the point of the some of the valid concerns. Which is, their particular iMac is considerably louder than other iMacs doing the same tasks. Sure, it still may be a lot quieter than a desktop of 10 years ago, but if is it notably louder than other similarly configured macs, then that could be a cause for concern.

Frankly, I would avoid the i7's anyway. They create more heat and fan noise, and the advantages of hyperthreading is dubious at best. Even in idealized benchmarks HT gives you about a 20% jump in performance, but afaik very little software even leverages much if any, of that extra power.

 

[EugW]

I think you're missing the point of the some of the valid concerns. Which is, their particular iMac is considerably louder than other iMacs doing the same tasks. Sure, it still may be a lot quieter than a desktop of 10 years ago, but if is it notably louder than other similarly configured macs, then that could be a cause for concern.

Frankly, I would avoid the i7's anyway. They create more heat and fan noise, and the advantages of hyperthreading is dubious at best. Even in idealized benchmarks HT gives you about a 20% jump in performance, but afaik very little software even leverages much if any, of that extra power.

Video encoding easily leverages the extra power provided by hyperthreading. However, since I don't do that very often, and because I place significant value in quietness, I downgraded to the i5 without HT.

As mentioned, with the i7 7700K, for one short clip I was getting a 10 minute encode, but over 9 minutes of that in loud fan mode. With the i5, the same clip took 12.5 minutes, but it was quiet the whole time.