Imac 24" early 2008, CPU heat problem

[domajean]

Hello everyone,

I use my iMac a lot and even more these days for audio purpose. When I do so, my good old iMac begins to accuse his age and the cpus are running wild...and not only that, the rest of the components are also getting hot.

With SMC Fan control, I often need to push the fans to the limit when I have a lot of plugins running at the same time. I tested individually the 3 of them and they are all fine, so it is not the source of the problem. 3 months ago I was using around the same amount of plugins without this overheat problem.

3 parts of my iMac have been changed:

The graphic card was a Geforce 8800 and like a lot of you already know, those are a real time bomb. I had to downgrade my video card to the ATI Radeon HD 2600 Pro(I actually like a lot more this video card)

I upgraded the ram with 2 X 2GB

The Initial Western Digital HDD has been changed for a SEAGATE 2TB model ST2000DL003-9VT166

Also I cleaned all the fans when I changed the HDD in summer 2011.

I performed an extended Hardware Test a couple hours ago and an error came up:

4MOT/2/40000006:HDD-1369

Looks like I got an Hard drive problem. Is it a separate problem? I have no clue for now.

Somebody on another forum wrote the following:

I had a similar problem, turned out that the temperature sensor of the HDD was broken (even though iStat reported CPU fan). The HDD needed to be replaced to fix this (luckily I have AppleCare).

Would it be possible that the problem is coming from there for that error? Is there a way to know more about this?

Maybe I need to change the cpu paste? I really don't know. But now working on my Mac is a little bit stressful since I always need to monitor all the components temperatures with temperature monitor and SMC Fan. When I push the fans really high while composing, the heat of practically everything is between 50 and 60 degrees, cpu often over 55. I fear for the damage that this heat could cause and the sound of these fans is really killing my workflow!

Thanks for your time and future help.

Dom

 

[domajean]

Here's an example of heat jump that I get sometimes:

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It is really hard to come back to normal heat when it starts to warm up like that, I often need to close everything and wait.

Could that error with the hard drive be the cause? I did have some problems with the hard drive for a while, it seems really unstable if I compare it to my previous one that came with the iMac...

Thanks again for future help.

Dom

 

[Intell]

Those templates are all normal if not slightly lower than normal for an Intell aluminium iMac.

 

[domajean]

Hi Intell, thanks for your response.

The fans, during that moment, were all at top speed, and it was impossible to go down. I never had such a hard time with the heat of my components before. Right away when I use something that demand a fair amount of processing, the heat jumps high right away and if i don't push the fans to top speed, a kernel panic will pop.

So I don't remove the possibility of being that I am stressing for nothing, but this is the first time I have to deal that much with heat...

 

[GGJstudios]

When I push the fans really high while composing, the heat of practically everything is between 50 and 60 degrees, cpu often over 55. I fear for the damage that this heat could cause and the sound of these fans is really killing my workflow!

Your temps are low-to-average. There is no cause for concern. The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C (221F), GPU Tjmax = 100C (212F) on i3, i5, i7 processors. (Source: Intel)

If you're not already using it, iStat Pro (free) or iStat Menus ($16) will give you accurate readings of your temps and fan speeds, among other things.

Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If you're constantly putting high demands on your system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just your Mac doing its job to maintain temps within the normal range.

It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.

Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level.

If your fans are spinning up without increased heat, try resetting the SMC.
(PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)

The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks (except the new MBP with retina display, which has intake vents along the sides at the bottom). The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best.

Learn about the fans in your Mac
Apple Portables: Operating temperature

For Flash-related issues:

• Find your Flash version and make sure it's the latest version available.
• Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
• Use the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.)

I am stressing for nothing

This ^

 

[Intell]

Something is very wrong with the heatsink/CPU contact with your iMac. This is probably because you replaced the video card and may have done it incorrectly.

 

[GGJstudios]

Something is very wrong with the heatsink/CPU contact with your iMac. This is probably because you replaced the video card and may have done it incorrectly.

What makes you say that? The temps look quite normal, as you stated earlier.

 

[domajean]

Hi GGJstudios, thanks for your informative post.

But as I said, I control the speed of my fans with SMC Fan. I got one automatic shutdown 2 weeks ago because I was working on audio and didn't monitor my temps. My fans speed werent fast enough but I was doing normal work...like work that I was doing some months ago without putting my fans at top speed(over 4000 rpm).

Intell, Apple didn't want to change my video card with the ATI, Apple only change a video card with the SAME video card...which is quite stupid since that Geforce 8800 was born to brake on every users after around 2 years of use...

So I had to go to a specialized shop called Dalailamac, and the tech that was supposed to do the job wasn't available, so it's another tech with less specialization for that matter that did the job.

I though he did it pretty good, since I didn't have any problem for a good 1 year.

Also, it is imporant to note that the hard drive has been changed by myself with a Seagate, and right now I know that I need to replace it because I got an error during the Hardware test and when I am working on video or audio stuff I often have some issues occurring like the rainbow circle appears for practically no reason and things like that.

If I change the hard drive again, could that solve the heatsink issue? Or it is really not related?

 

[Intell]

What makes you say that? The temps look quite normal, as you stated earlier.

From what I understand based on the OP's somewhat confusing posts and vague information. The system's fans idle fine. But as soon as he tries to do anything taxing, the system will kernel panic. Unless he manually revs the fans up all the way. The temperatures are normal, but the OP did state that the fans were at their max at the time. I know if I make the fans on my iMac rev all the way, the CPU hits 100F, not 150F like the OPs.

 

[GGJstudios]

From what I understand based on the OP's somewhat confusing posts and vague information. The system's fans idle fine. But as soon as he tries to do anything taxing, the system will kernel panic. Unless he manually revs the fans up all the way. The temperatures are normal, but the OP did state that the fans were at their max at the time. I know if I make the fans on my iMac rev all the way, the CPU hits 100F, not 150F like the OPs.

It sounds like the OP is messing around with fans via smcFanControl. If they stop using that and let the Mac do its job, the fans will likely behave normally.

 

[Intell]

It sounds like the OP is messing around with fans via smcFanControl. If they stop using that and let the Mac do its job, the fans will likely behave normally.

I agree that it should be left alone. However, he also states that if he doesn't it will kernel panic. This could be caused by the hard drive becoming slightly too warm for it to handle in its assumed dieing state. Thus causing a kernel panic. I've not know a overheating CPU to cause a kernel panic, only an immediate shutdown.

One test the OP could do it to rev only the hard drive fan to see if this helps. I know that when the hard drive in my 7,1 iMac started to die, the increased airflow from the maxed hard drive fan kept it alive long enough for me to clone it. It would stop working if the fan was idle.

 

[killerrobot]

I had a 2008 iMac that gave me the same error and replaced the HD but it didn't fix the error. I did more research and found out that the HD Fan was the actual culprit of the error. When I replaced the HD fan, the error went away, my temps dropped to normal, and I never had any other problems.

EDIT: iStat always showed the fan working for whatever reason which is why I never suspected it would was the problem and SMC fan showed that I could change the speeds. So I thought it was very unlikely to be the cause, but it was.

 

[domajean]

Thanks for all your responses, it is greatly appreciated.

Killerrobot, I just did a test with my fans. I put the HDD one to max and left the other ones on 2000 rpm. When I did that, I did clearly hear the rising sound of the HDD fan. I think the fans are fine since I clean my iMac once a year.

The probability of an issue with the dying hard drive being quite high now according to the responses on this thread will be my priority.

I will change it, but if you guys could help me to choose a good one for a price around 100$ and that is compatible with my iMac and not complicated to install, it would be really helpful since I don't want to get another HDD that doesn't last for more than 2 years.

Thanks again, you all rock!

 

[killerrobot]

Well hopefully it's just the HDD then, but keep an eye on the fan because it was fooling all the sensors on my 2008 iMac.

As far as hard drives, I'd look on newegg.com for a good deal, although amazon has decent deals every once in a while as well. All the reviews from the people that actually have the drives come in quite handy. In these forums most have their preference, whether it be WD, Seagate, Samsung etc. IMO, just find the best deal you can on a disk that has a 3-5 year warranty and buy it regardless of the brand and always make sure to keep a back-up.

 

[domajean]

Hello,

Alright, will do some meticulous research before buying anything.

Thanks for your help and thanks to everyone who participated in this thread...will come back when I will have changed the HDD.

Dom