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Cooling in the new 2020 27" iMac?

My fans are on 'not full blast' right now. But they're a very audible 'WHHHHHHRRRRRRRRRRRRR' and the machine is doing nothing. I don't count having 4 3D apps open and doing nothing a stress test, though.

Just randomly coming on. For several mins.

I've opened my skylight for a bit of cool air. It's going to be a long winter if it keeps on like this.

I wonder if iMacs are sensitive to ambient temperatures. But it's not especially hot today. *Chill breeze in the air.*

Azrael.
 
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Screenshot 2020-09-11 at 13.19.04.png


Taxing.

Azrael.
 
Opening Blender increased my CPU temp by 0.22C for about 3 seconds. No fan speedup at all. I'm back down to 39.20 now.
 
...and another random pulse of fan 'noise.'

(No...it doesn't sound like a 'jet engine...' but it does sound obvious and loud out of nowhere.

As for 'nervous', I can understand if somebody who has bought one and hears this maybe wondering what's going on.

Azrael.
 
PBG4 Dude said:
Opening Blender increased my CPU temp by 0.22C for about 3 seconds. No fan speedup at all. I'm back down to 39.20 now.
Click to expand...

I've still got Blender open. 'Doing nothing.' Fans have sped up. Random intervals of 'blowing noise' (as defined by each's user's instanced reality...)

...I'm going to keep it open see if this pulsing behaviour...continues... (ah...there it goes again...)

All the other apps have now been closed. Just Blender open.

Azrael.
 
Azrael9 said:
...and another random pulse of fan 'noise.'

(No...it doesn't sound like a 'jet engine...' but it does sound obvious and loud out of nowhere.

As for 'nervous', I can understand if somebody who has bought one and hears this maybe wondering what's going on.

Azrael.
Click to expand...
Did you set up your iMac as a new machine or did you migrate an existing setup to it?
 
It's 'as is' as new. Bar the supplemental update I put on yesterday.

I did benching to begin with. And yes. Unigine will provoke a low key response to the gpu over time. Cinebench. The fans will kick in towards the end. Blender 3D benches hammer the fans from the off. Loudest I've heard them.

I installed all my apps in the last few days. Affinity Photo, Design, Publisher. These don't even provoke a fan response.

Lightwave 3D. No. Not unless rendering. Poser 3D. No. Not unless rendering.

Z-Brush. (See pic above.). Fan response for opening the 'Lightbox.' (*raises a somewhat annoyed eyebrow.)

Blender 3D. (See pic above.). But the for the mere presence of having it open on my machine. It 'seems.'

I also noted. The iMac 'seems' touchy about the ambient temp' of a room. Degree 22. I'm in an attic studio environment. But it's not the tropics. Occasional pulse of fans with not a great deal happening on the iMac.

Blender 3D. Still open. Fans haven't pulsed in a while. But then. The attic window has been open for a while. Just shut it because its beeping freezing. :p

Short answer. No. I didn't migrate an existing set up to it.

Azrael.
 
Loaded up Z-Brush again. Sitting idle.

Alongside Blender. Sitting idle.

Fan noise. 'Blowing.'

Room temp. 'Cool.'

Azrael.
 
My old MBP15 does the same. Opening apps, even Safari, will make the fans ramp up. Even more on Big Sur. I remember I told you that Beta 6 was a bit colder, but in fact it’s not. The MBP is only silent when displays are shut. 30 seconds after screens are woken up fan speed is 75%. This is insane. Or I have something wrong (the battery is swelling) and all fans spin because of that or really there is an efficiency problem with MacOS and CPU time consumption.
 
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pldelisle said:
My old MBP15 does the same. Opening apps, even Safari, will make the fans ramp up. Even more on Big Sur. I remember I told you that Beta 6 was a bit colder, but in fact it’s not. The MBP is only silent when displays are shut. 30 seconds after screens are woken up fan speed is 75%. This is insane. Or I have something wrong (the battery is swelling) and all fans spin because of that or really there is an efficiency problem with MacOS and CPU time consumption.
Click to expand...

Yes. I do recall you had issues with the MacBook Pro. 75% fan speed for being 'woken up.' Fan Noise and MacBook Pro is something I've looked at from a distance for some time.

Well. As the 1st time I've experienced this on a Mac (than fans whirring up because they actually doing strenuous compute...) it seems very odd behaviour.

I did turn off the internet. And the fans went away.

Maybe this needs a firmware fix to set the bench lower...maybe the boost clock is too much for the inadequate cooling. That's the impression I'm getting.

... random fans blowing in and out. Don't think that's good enough. Not from where I've come from on the last iMac.

Certainly not for the price.

Azrael.
[automerge]1599829833[/automerge]
Fan is currently blowing away. The machine is doing 'nothing.'

Unless you count Poser 11 and Z-Brush being open as something.

Azrael.
 
erg100000 said:
The fan ramped up to 2500RPM everytime I (just) started Photoshop. You cant tell me that this is fine...
Click to expand...

man, I gotta say I think your specific computer is a lemon or you’re doing something wrong. I have the i7, almost stock just upgraded to the 1TB SSD And I have 64GB if Samsung RAM in, removed the stock RAM. And it’s dead silent for me. I pushed it the other day running A big Logic file, had PhotoShop opened and was rendering a HD video in After Effects...no fans, no noise, not even a warm Chassis. And I’m in a sound proof music studio so I’m sure it’s silent or the noise is so low I can’t perceive it. Actually, it sounds like it’s unplugged, it’s THAT quiet.

since I bought this for a music studio I was considering the iMac Pro for the cooling. Man am I glad I didn’t get it. Saved a ton and this one is dead quiet.

I came back to this site because I saw so many people complaining about noise and it’s just mind boggling to me. This is the quietest machine I‘ve ever had. Maybe I’m not pushing it hard enough but your saying just opening photoshop sets the fans off...I’m not getting that.
 
jobinhosyntax said:
Didn't you hear? iMac aren't for using blender. They're for browsing Pinterest and buying iPhones on.
Click to expand...

They're for a little bit more than Pinterest and Internet shopping. ;)

They're capable. But the cooling is 'off.'

As in, I don't know how this erratic fan noise got past Apple's Q&C.

Azrael.
 
filmak said:
Is this a proof that the 8 core runs cooler? Azrael owns a 10 core one, I think?
What do you think?
Click to expand...

Well. At least, that hypothesis would stand some investigation.

I can only report on my 'early days' investigations. From benchmarks. To applications.

8 core vs 10 core. It's not like recent Intel CPUs have draped themselves in efficiency glory. Otherwise Apple wouldn't be going AS.

Azrael.
 
Mr. Warbles said:
man, I gotta say I think your specific computer is a lemon or you’re doing something wrong. I have the i7, almost stock just upgraded to the 1TB SSD And I have 64GB if Samsung RAM in, removed the stock RAM. And it’s dead silent for me. I pushed it the other day running A big Logic file, had PhotoShop opened and was rendering a HD video in After Effects...no fans, no noise, not even a warm Chassis. And I’m in a sound proof music studio so I’m sure it’s silent or the noise is so low I can’t perceive it. Actually, it sounds like it’s unplugged, it’s THAT quiet.

since I bought this for a music studio I was considering the iMac Pro for the cooling. Man am I glad I didn’t get it. Saved a ton and this one is dead quiet.

I came back to this site because I saw so many people complaining about noise and it’s just mind boggling to me. This is the quietest machine I‘ve ever had. Maybe I’m not pushing it hard enough but your saying just opening photoshop sets the fans off...I’m not getting that.
Click to expand...

Have you tried doing any 3D rendering? Specifically.

Ironically. The chassis is very cool. Mine was also very quiet rendering HD video.

Certainly, I didn't expect the fans to pulse in for loading 3D apps or keeping them open with nothing happening.

Azrael.
 
276990 said:
Build a PC.
Click to expand...

Ironically, my plan was to have an iMac for general production (and some 3D) and the dual Mac PC workflow for the PC to do the 3D heavy lifting.

There's nothing wrong with the iMac's performance. But the thermals have a question mark over them. And yes. It does depending on the 'work' type at hand.

For some. If you're going to get fan noise anyway. A PC may be an alternative solution. Certainly for a 3D workload.

Rendering 3D I'd expect the fans to kick up somewhat of a fuss. To be expected.

But not for opening a 3d app and it sitting idle.

It maybe that the turbo boost is set too high...and is somewhat touchy about the process at hand. Something that could be cured with a firmware patch by Apple?

I might just have a chat with Apple about this. I'm liking the power. That is not in question. But clearly, the thermal's haven't been kept in check with software/hardware cooling solution... (that's Apple's area...) and whilst Intel have brought their 10 core performance here (not far off a 1st gen Threadripper...) and the AMD brought their last year mid range gpu here... they've both struggled to keep efficiency in check. There's a bit of accountability to go all around.

I'm just doing 'what I did on my last iMac' nothing that onerous. Outside of the benching and testing the current 3D render speed limits. And of course if you do either of those you're pushing the machine. Ofc. Fans to be expected. 3D rendering will push a tower let alone an A.i.O.

Anything 2D. Rendering HD. Not a problem. I'm not a Logic user. But I haven't seen any comments about it being anything other than being a good citizen.

Azrael.
 
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jobinhosyntax said:
Didn't you hear? iMac aren't for using blender. They're for browsing Pinterest and buying iPhones on.
Click to expand...
Screenshot 2020-09-11 at 16.32.23.png


I'm guessing your comment was tongue in cheek. Otherwise. Certainly not.

This render here was blazingly fast with a typical response from the fans. But it is an order of magnitude faster.

My 2012 iMac quad core fans didn't kick in for such renders in Poser 11. But it wasn't a 2020 iMac 10 core 14+++++++ cpu with 2012 cooling. I guess.

There's nothing wrong with the performance chops.

Against. No complaints for the fans kicking in for a 3D render.

But not for opening an app and displaying an interface.

Azrael.
 
Just a footnote.

Blender and Poser have now been open for hours. No pulsing fans.

Hm.

Azrael.
 
Azrael9 said:
I wonder how this turbo yo-yoing effects the life span of components. 0-60mph then slamming the breaks on. As to a more measured response to a performance task.


I guess the other thing is...is the turbo just on 1 core, 2 cores...or all cores that is causing this 'flush' of heat.

Azrael.
Click to expand...

These are great thoughts. I do think the turbo is just on just one or two cores, and it does drastically heat up the processor (and thus surrounding components). Furthermore, these pretty fast swings of temps surely can't be ideal for not only the processor, but those surrounding components.

And then I ask myself: If turbo boost only kicks in for really short spurts, like a few seconds, is it really saving me any time worth noting? I mean, if a 3second process takes 3.5 seconds without turbo boost ... is that worth it? I think not.

And don't even get me started on hyper threading, which seems to be even more useless:

 
Last edited:
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Mr. Warbles said:
man, I gotta say I think your specific computer is a lemon or you’re doing something wrong. I have the i7, almost stock just upgraded to the 1TB SSD And I have 64GB if Samsung RAM in, removed the stock RAM. And it’s dead silent for me. I pushed it the other day running A big Logic file, had PhotoShop opened and was rendering a HD video in After Effects...no fans, no noise, not even a warm Chassis. And I’m in a sound proof music studio so I’m sure it’s silent or the noise is so low I can’t perceive it. Actually, it sounds like it’s unplugged, it’s THAT quiet.

since I bought this for a music studio I was considering the iMac Pro for the cooling. Man am I glad I didn’t get it. Saved a ton and this one is dead quiet.

I came back to this site because I saw so many people complaining about noise and it’s just mind boggling to me. This is the quietest machine I‘ve ever had. Maybe I’m not pushing it hard enough but your saying just opening photoshop sets the fans off...I’m not getting that.
Click to expand...
How heavy was huge logic project. Number of tracks / vsts / reverbs / gulfosses etc?
 
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