Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

Aluminium iMacs overheating?

vtprinz said:
Why should it handle heavy gaming at the default settings?
Click to expand...

Leon Kowalski said:
It should handle anything with no user settings/adjustments of any kind.
That's why Apple installed three software-controlled variable-speed fans
and about a dozen temperature sensors. The firmware is supposed to
continuously monitor the internal temperatures and adjust the fan speeds
automatically.
Click to expand...

Wow, I actually agree with Leon Kowalski. It must be snowing in hell.

...the problem is, many iMacs don't seem to be doing that,

LK
Click to expand...

If you say so. I can only speak for my own machine. I play quite a bit of Call of Duty 4 and Bioshock and have never bothered to check what temps the machine is running at since I have not experienced any problems. I expect that the machine is running hot but as you say above I also expect the machine to adjust its fan speeds accordingly and as needed. I do not run any 3rd party fan control programs.
 
durija said:
Maybe I don't need this stuff, but I have installed and run Temperature Monitor and smcFanControl on my iMac. There are no apparent problems so far. And I must say that being able to see all those temperature readouts and then actually being able to adjust the fans to control them has given me some peace of mind. Sometimes a security blanket can make a difference in your computing quality of life. Relaxing now.
Click to expand...

I have a security blanket as well. It's called the one year limited warranty and AppleCare for the next two years after that. That said I have no expectations that using my iMac to play games should in any way be "dangerous" for it.

If I was experiencing any graphical glitches or artifacting as the OP seemed to imply he was seeing I would send it in to Apple for service immediately. It may have had a bum GPU from the start.
 
AlexisV said:
They seem to have two settings - normal and 'emergency cooldown'.

You'll see the cooldown phase when it's under full load, in a very hot room
with the sun shining on it for example. I've only seen it once, last year.
The fans come on for about 3 minutes and it sounds like a vacuum cleaner.
Click to expand...

Maybe that's what you see, but the fans in my iMac adjust gradually
and continuously in response to internal temperature changes -- as
the designers almost certainly intended. Apple didn't install three DC
fans with digital speed-control and tachometer feedback just to have
two speeds: idle and panic.

Here's a handy little freeware app that lets you dial-in additional CPU
loading. If the fans don't respond by smoothly increasing speed as
the processor temp rises, your temperature control system is busted.

http://www.bresink.com/osx/SystemLoad.html

When some iMacs have effective fan control, and some don't, it's
a safe bet that they're not all working as the designers intended.

LK
 
Take a look at new iMac, it doesnt have much space for air movement. The back is nearly sealed up. I like the idea of airflow and cooler electronics. As stated earlier Apples fan flow solution allowed my cpu to get to 55 C now its 50 with smcfan and fans still cant be heard unless you put your ear next to the machine. Just a few tweaks on rpms.
 
I'd rather be sure what the problem is before sending it off to Apple. It's a lot of hassle.. it means taking a day off work to wait for a courier to pick it up, being without it for a while and then taking another day off to wait for it to be delivered. If they replace it there is also the added risk of getting one back with dead pixels or something.

Also, as I haven't seen the issue occur in other games (I don't care what anyone's opinion of SL's graphics are, this is the only one I've 'played' that seems to have pushed it to that level of heat) Apple would most likely just blame the app.

I've built computers... if the heatsink wasn't on right or the thermal paste wasn't applied properly, the case wouldn't be heating up because the heat wouldn't be transferred, the chip would sit there sizzling away to itself no matter how fast the fan is going. It just doesn't seem to speed up the fans at all without a third party app. IIRC, Apple did actually prove this point in one of their firmware updates (iMac Update 1.0 I think it was called) which was supposed to address the issue - or a similar one - but it doesn't seem to have worked for mine perhaps because it wrongly thought it didn't need it.

If it gets to the point where I can easily prove that there is a fault with the machine, then yeah it'll be time to send it off and deal with the related chaos.
 
macs have ALWAYS run hot. get used to it.

try putting a powerbook G4 on your lap for 20 minutes and tell me if you have any skin left!

Put 2 powermac G5's in a room and shut off the heat...it'll be plenty warm with them running.

its just a fact that macs have always run hot, G4's are notorious for heat, PowerMac G5's have a zillion fans in them and I'm sure the new intels are no different.
 
Leon Kowalski said:
Maybe that's what you see, but the fans in my iMac adjust gradually
and continuously in response to internal temperature changes -- as
the designers almost certainly intended. Apple didn't install three DC
fans with digital speed-control and tachometer feedback just to have
two speeds: idle and panic.

Here's a handy little freeware app that lets you dial-in additional CPU
loading. If the fans don't respond by smoothly increasing speed as
the processor temp rises, your temperature control system is busted.

http://www.bresink.com/osx/SystemLoad.html

When some iMacs have effective fan control, and some don't, it's
a safe bet that they're not all working as the designers intended.

LK
Click to expand...

I'm testing this right now, not exactly sure how but I'll increase the % by 10 and so on.
---

I stopped, putting the CPU at 100% on both cores wasn't really "skyrocketing" the temperatures, at most it got to a 45C. I think I would rather test the GPU, that would get better results than testing the CPU. After all, I always see the GPU's temp higher than the CPU.
 
KJmoon117 said:
I stopped, putting the CPU at 100% on both cores wasn't really
"skyrocketing" the temperatures, at most it got to a 45C.
Click to expand...
That's good -- the CPU temp isn't supposed to "skyrocket." If the fan control
system is doing its job, the fan speeds should increase smoothly & gradually
as the CPU temperature starts to rise. Of course, you'll need something like
iStat Pro ( from http://islayer.com ) to monitor the fan speeds.

I think I would rather test the GPU, that would get better results than testing
the CPU. After all, I always see the GPU's temp higher than the CPU.
Click to expand...

I agree. It's much more interesting to watch how the fan speeds react to
changes in GPU and hard drive temperatures. Unfortunately, I don't have
any handy-dandy tools for setting GPU or HD loads to known, repeatable
"stress levels." Without that, there's no good way to compare the results
between machines.

LK
 
Well I have iStat Pro so that's one of the reason I got smcFC due to the GPU getting up around the 60s (ºC) but the fan speed didn't change at all when both cores were at 100%.

I guess the fans start changing when it gets around 50ºC or so since the CPU only got up to 46ºC.
 
KJmoon117 said:
I guess the fans start changing when it gets around 50ºC or so
since the CPU only got up to 46ºC.
Click to expand...

I don't use smcFanControl; my machine stays comfortably cool without it.

My CPU Temp Diode normally runs at 35-37C with the fans loafing at idle.
When I set the CPU load to 100%, the fans stay at idle until the CPU Diode
reaches about 47-48C, then all three fans speed-up gradually and stabilize
at 200-250 rpm above idle, with the CPU Diode holding steady at 51-52C.

BTW, 52C is a conservative CPU operating temp; Intel specs 100C max.

If I wasn't watching temps and rpms, I wouldn't be aware that anything
had happened; a gradual 200-250 rpm increase in fan speed isn't audible.

If your smcFanControl is set a few hundred rpm above idle, that's probably
enough to keep the CPU temp below the 47-48C 'threshold', even at 100%
load. In that case, I'd expect exactly what you describe -- no change in fan
speed at 100% CPU load.

...did you try it with smcFanControl disabled?

LK
 
Of course (trying it with smcFanControl set to Apple default then I quit the application).

However, what you said differs from my 20" 2.0 Alu iMac temperature. If I don't have my fans at smcFC setting then my temperature goes around high 40ºC (idle).

My default smcFC settings are (rpm)
Optical Fan 1500
Hard Drive Fan 2500
CPU Fan 2000

Apple's settings are (default settings)
Optical Fan 1400
HDD 1600
CPU 1600

My temperature currently (under smcFC default, running for a while idle)
Picture2.png
 
KJmoon117 said:
Of course (trying it with smcFanControl set to Apple default then I quit the application).

However, what you said differs from my 20" 2.0 Alu iMac temperature. If I don't have my fans at smcFC setting then my temperature goes around high 40ºC (idle).

My default smcFC settings are (rpm)
Optical Fan 1500
Hard Drive Fan 2500
CPU Fan 2000

Apple's settings are (default settings)
Optical Fan 1400
HDD 1600
CPU 1600

My temperature currently (under smcFC default, running for a while idle)
Picture2.png
Click to expand...

My observation is that when I wake up from sleep and the temperature for HD1 is around 28-32ºC and if ran at default settings (smcFC) then the temperature stays in the high 30s. Once I do something big (gaming or something intensive) or switch back to Apple's setting it will stay in the low 40s.

I guess my iMac has something strange going on hehe.
 
I'm curious whether the speed is only controlled by the CPU temperature, in which case if you're doing something (game or whatever) which is graphically intensive but not CPU intensive the GPU will just heat up through lack of airflow. This may explain why I don't see the same symptoms in EQ2, WoW etc. Will have to see how much of the CPU they use...

Oddly, textedit was occasionally "flicking" last night as if another app was getting the focus for a few milliseconds. It didn't happen in any other app so I don't know if it's just a bug or something.

Does anyone here with 20" Alu iMacs get weird graphics under Windows, or more to the point *not* get it? Makes me wonder if something is actually faulty, but the thing is it doesn't happen whilst booted into OS X - what happens under Windows is certain shades of grey/blue have feint diagnonally scrolling "fuzzy" patterns, kind of like an interference effect. Other shades are "stripey". It's noticeable in the sky on the "Bliss" wallpaper. I had it down as a difference in dithering between the Windows and OS X graphics drivers (it being a 6 bit panel and all) but I'm not so sure now.
 
Cloudane said:
I'm curious whether the speed is only controlled by the CPU temperature, in which case if you're doing something (game or whatever) which is graphically intensive but not CPU intensive the GPU will just heat up through lack of airflow. This may explain why I don't see the same symptoms in EQ2, WoW etc. Will have to see how much of the CPU they use...

Oddly, textedit was occasionally "flicking" last night as if another app was getting the focus for a few milliseconds. It didn't happen in any other app so I don't know if it's just a bug or something.

Does anyone here with 20" Alu iMacs get weird graphics under Windows, or more to the point *not* get it? Makes me wonder if something is actually faulty, but the thing is it doesn't happen whilst booted into OS X - what happens under Windows is certain shades of grey/blue have feint diagnonally scrolling "fuzzy" patterns, kind of like an interference effect. Other shades are "stripey". It's noticeable in the sky on the "Bliss" wallpaper. I had it down as a difference in dithering between the Windows and OS X graphics drivers (it being a 6 bit panel and all) but I'm not so sure now.
Click to expand...

Cpu intensive or not it's always in a high usage, but that's not all, both cpu and gpu share the same heatsink, so, when one heats up, the other will raise a bit also.

In a closed room at 28ºC gaming C&C 3 for 2 hours with fans at 2500rpm I get around 55ºC CPU and 75ºC/79ºC. Without smcfancontrol the fans will only rise till 1600rpm. Imagine the temps at those fan speeds...
 

Attachments

  • DSC_3824.jpg
    DSC_3824.jpg
    89.4 KB · Views: 168
  • DSC_3847.jpg
    DSC_3847.jpg
    95 KB · Views: 144
I put all the fans up to full power, and played call of duty 4 for 3 hours, it ran pretty smoothly, and the right side of the iMac was cool to touch, the left side was room temp.

IT SOUNDED LIKE A ROCKET!:eek:
 
PMR said:
Are you saying that 1600 is your default setting for Apple products?...

Because the iMacs come with the following: HDD:1200, CPU/GPU:1200; Optical:1000.
Click to expand...

Well... I was generalizing, I thought Apple would make fan speeds uniformed (within the same products).

My reason for my thought is that smcFanControl doesn't let you set your fan speeds lower than Apple's built in settings and the lowest I can set it to is at those fan speeds. Plus, the fans rpm were at the same rpm before I installed smcFC.

I have a 20in 2.0ghz Alu (Intel/Leopard) iMac. You? The fan speed could be different if you were to compare with a different product/firmware/etc...

MrT8064 said:
I put all the fans up to full power, and played call of duty 4 for 3 hours, it ran pretty smoothly, and the right side of the iMac was cool to touch, the left side was room temp.

IT SOUNDED LIKE A ROCKET!
Click to expand...

I wouldn't push it that high, that could prematurely burn out the fans or wear & tear the bearings.
 
PMR said:
Because the iMacs come with the following: HDD:1200, CPU/GPU:1200; Optical:1000.
Click to expand...


That's funny. My system reports Optical at 800, I forget the HDD and GPU/CPU at the moment since I'm not home. But I don't run any applications to adjust fan speed either.
 
My 24" Alu iMac's default fan speeds are:
cpu = 1200
gpu = 1200
odd = 700

I have put my default speeds of:
cpu = 1401
gpu = 1755
odd = 700
 
johto said:
My 24" Alu iMac's default fan speeds are:
cpu = 1200
gpu = 1200
odd = 700

I have put my default speeds of:
cpu = 1401
gpu = 1755
odd = 700
Click to expand...

Really strange... I just woke up from sleeping (both my iMac and I) and checked. iStat is reporting the default fan speeds (CPU= 1200, 1200, Optical I couldn't check, turned on smcFC after I realized the GPU is running at 50ºC idle).

My default speed still remains for smcFC at 1500ODD, 2500HDD, and 2000CPU.
 
Cloudane said:
I just knew some stupid fanboy would steam in telling me it's my fault for trying to actually run something on the thing (naughty me),...
Click to expand...
I'm not going to say it's your fault, but I am not sure it's right for others to say it's Apple's fault either.

I play Second Life (well not for a while lately), and I've never had the problem of which you speak on the aluminium iMac or any other machine. When I started, I used the passively cooled iMac flat-panel sometimes for literally 12 hours straight and had no heat problems at all. Similar with my G4 tower etc.

I would think this is an actual hardware/software fault, and not the typical behaviour of an aluminium iMac or the typical settings that Apple gives it.

At the very least, the fan system is supposed to be intelligent enough to ramp up the blowers on it's own when it detects excessive heat build-up. So the behaviour should have been that the fans escalated louder and louder until the graphics chip burnt out. If the machine did not do that then that's a fault in my book, not correct behaviour. Seems to me it's the failure of the fans to respond to the heat that fried the chips (if they are fried).
 
I been noticing above normal temp on my iMac lately. I also noticed that i need to find a new home for my PS3. The PS3 exhaust was blowing hot air directly into my iMac. After 1 hour of playing PS3 my iMac froze up while it was only rendering the screen saver.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back