iMac overheating?

[Apocrathia]

So I've been having trouble with my new iMac that i purchased recently (26th of August actually). Whenever I'm doing something CPU intensive, the machine just shuts off, but usually it's not right in the middle of whatever I'm doing, it's after I close the application. For example: I was playing SimCity4 the other day, pretty old game to cause this problem I would think. As soon as I exit the game, the system shuts off. No warning, nothing, just shuts off. This will happen when i close VMs (it actually happened yesterday while I was running the VM), etc...
So I've reset the SMC/PMU, PRAM/NVRAM, and I've even reseated the RAM. Still the same problem. I've taken it in to a repair center in town, hoping I'll get it back by the end of the week.
Does anyone have any idea why this would be happening?

 

[Hellhammer]

Immediately call to Apple, that's not normal. Your PSU is likely defective or logic board

 

[trose]

Sounds more like a bad RAM stick to me.
Download a utility to check your CPU temp, run a CPU intensive app (such as a game) for 20 minutes, then check what the CPU temp is at. Then report it back here.

I'd think it's RAM if it's most often occurring after you quit a program, not while running. This is when a bunch of memory would be flushed back into the pool.
Just a guess...

 

[Apocrathia]

Sounds more like a bad RAM stick to me.
Download a utility to check your CPU temp, run a CPU intensive app (such as a game) for 20 minutes, then check what the CPU temp is at. Then report it back here.

I'd think it's RAM if it's most often occurring after you quit a program, not while running. This is when a bunch of memory would be flushed back into the pool.
Just a guess...

That was my thought as well (I probably should have included this). Most Linux CDs come with memtest86 loaded on them, so I grabbed an ubuntu 9.04 disc and ran memtest overnight to check for any errors. Nothing.
I would have tried swapping the ram with some kingston I have in my mac mini because I know memtests can lie sometimes, but I didn't feel like removing the heat spreaders and voiding the warranty so that I could test it out.

Also, the system is sitting on an APC XS-1500 UPS. So it's getting "clean" power. I thought it might have been a PSU error as well. Since it can't be the source. I keep a mac mini, linksys wrt610n router, and my drobo on the backup stage of the UPS and I have never had any problem with them before.

 

[iLog.Genius]

I think Apple Hardware Test will find something and report an error.

 

[Apocrathia]

I have already called Apple, opened a case, and the machine is sitting at my local repair center right now. I still wanted to post my problem on to here and see if I could get any suggestions. Anything I may have missed when I was troubleshooting. I'm pretty sure it's either the logic board or the PSU as well though.
I hope I can get my system back by the end of the week though.

 

[Apocrathia]

I think Apple Hardware Test will find something and report an error.

You get to that by booting the system and holding "D", right?

Tried that last night and nothing would come up. I sat there holding the button for a good 10 minutes. I was almost tempted to find something to keep it held down with.

 

[trose]

Hmm, ya, sounds like you've done just about everything you could.

I'm guessing PSU/logicboard as well.
Hopefully you're still under Apple warranty? Logicboards can be pricey!

Crossing my fingers for you.

 

[Apocrathia]

Hmm, ya, sounds like you've done just about everything you could.

I'm guessing PSU/logicboard as well.
Hopefully you're still under Apple warranty? Logicboards can be pricey!

Crossing my fingers for you.

I wanted to check to see if there was anything else that anyone could suggest that I didn't already do. It makes me feel a little bit better knowing that it wasn't just something stupid that I could have fixed.

It's still under warranty thankfully, a 3.06ghz imac logic board would definitely be expensive!

 

[thermodynamic]

Sounds more like a bad RAM stick to me.
Download a utility to check your CPU temp, run a CPU intensive app (such as a game) for 20 minutes, then check what the CPU temp is at. Then report it back here.

I'd think it's RAM if it's most often occurring after you quit a program, not while running. This is when a bunch of memory would be flushed back into the pool.
Just a guess...

iStat Pro is probably good -- works great on my macbook pro, but I am getting erroneous readings on my imac -- I did note which version was meant for which device...

 

[1ede2]

I'm also having a similar problem. I bought my imac 3 days ago and I also have another post, "loud fan", here.

I dl'ed istat. My temps and RPMs are as follows;

CPU fan: 3894 rpm
Hard drive: 1601 rpm
Optical drive: 4604 rpm
TEMP;
North bridge: 108
HD Bay: 93
HD Temp: 95
Optical drive: 88
Mem Controller: 88
CPU: 82
ambient: 72
CPU heatsink: 82

This is just starting it up after being away at work all day. Not running anything....ugh. Sounds like a dust buster its so loud too.

 

[Poncho]

Here are my readings. 24in al iMac.

BTW, as a rule fans should sit at 700, 1200 and 1200rpm (Opt, HD, CPU).

 

[Apocrathia]

I use iStat Pro on all of my machines. I don't feel right without it.

My CPU fan never seemed to go above 1200RPM and even after running a game for a while, my CPU didn't go above ~58°C.

I don't have my system in front of me, so I can't really give a good reading. But this is just what I noticed. So maybe the sensors are just off/dead, and that's what causing the fan not to kick in.

I also tried using smcFanControl to turn the fan on high and had no luck with that either.

 

[Lordedmond]

You get to that by booting the system and holding "D", right?

Tried that last night and nothing would come up. I sat there holding the button for a good 10 minutes. I was almost tempted to find something to keep it held down with.

you did put the dvd install disk in , the one that came with you iMac before you booted ? and held 'D'

 

[Apocrathia]

you did put the dvd install disk in , the one that came with you iMac before you booted ? and held 'D'

That's what I did wrong, I forgot it was actually on the install disc. Doh!

I'm probably going to call the service center today to check up on it and see if they found anything yet. I'm curious as to what the problem is.

 

[1ede2]

I'm also having a similar problem. I bought my imac 3 days ago and I also have another post, "loud fan", here.

I dl'ed istat. My temps and RPMs are as follows;

CPU fan: 3894 rpm
Hard drive: 1601 rpm
Optical drive: 4604 rpm
TEMP;
North bridge: 108
HD Bay: 93
HD Temp: 95
Optical drive: 88
Mem Controller: 88
CPU: 82
ambient: 72
CPU heatsink: 82

This is just starting it up after being away at work all day. Not running anything....ugh. Sounds like a dust buster its so loud too.

Did anyone see my post!? This is only after having the mac on for 5 minutes!!

 

[Apocrathia]

Be thankful your CPU fan works at least. It might be the same problem I'm having though. I have a feeling it's a temperature sensor that's "off" and is reading adversely lower (or higher, in your case) temperatures, but it could also be the RAM or the PSU, as others have specified here.

Try resetting the SMC and see if that does anything, if not; call apple and get it taken care of if you still can.

I'm hoping that I'll have my iMac back by the end of the week. Maybe I'll get lucky and apple will just decide it'd be cheaper to give me a new system than repair the old one. (Old is a figurative term, the system is only 3 weeks old as it is now). I just hope that if they do that, they don't decide to give me one with that blasted ATI gpu in it instead.

 

[Apocrathia]

Just got off the phone with the service center, and apparently my iMac is spitting out the apple install disc with the diagnosis software on it and they can't get it to run the test. They seem to think it's the logic board or the ram as well.
Apparently, I just got a bastard machine. Maybe I will just get lucky and get a new machine.

 

[Apocrathia]

I got my system back today. According to the service center, my problem are caused by Snow Leopard???
It already did a random shut down on me though in the middle of running photo booth of all things. (I was trying to get a picture of myself because i just got back from the optometrist and my eyes are all dilated, so i can't see how bad my eyes look right now.)

Does anyone have any further advice or things that they would suggest i try?

 

[Apocrathia]

does anyone have any ideas? please, this is happening more and more frequently and there is nothing that i can find out about it other than there is some hardware issue that AHT is not detecting...
I am going to be calling apple in the morning.

 

[Mugwumper]

Something's not right - obviously . . .

does anyone have any ideas? please, this is happening more and more frequently and there is nothing that i can find out about it other than there is some hardware issue that AHT is not detecting...
I am going to be calling apple in the morning.

I don't understand - the repair center gave your system back, even though
they couldn't read a disk? And they are saying software is the cause? So
how they expect you to do anything if you can't load a disk?

Do you happen to have a Leopard install disk? If so, and you can get it to
boot from that disk, I'd try an "archive and install". Of course, run some of
the disk utility checks . . . Then download a 10.5.8 combo and do the update
and see what happens. Then maybe do the Snow Leopard update . . .

If not (and you only have Snow Leopard), can you boot that disk? If so, can
you get anything to work from the install disk? If it's stable enough, see if
you can do a clean install . . .

Very strange . . .

 

[Apocrathia]

Yeah, it makes no sense to me either. I bought my computer like 2 days before Snow Leopard came out. So I still have the original Leopard discs. I've actually run the AHT already tonight with no errors. I'm now running it a second time, and tomorrow I'll probably make a 3rd run to be sure nothing is wrong with my hardware (as far as the AHT can determine).
Like I said, I will be calling Apple in the morning, the service center here in town literally did not do anywhere near as much troubleshooting as I have.
I will probably do an archive and install tomorrow after I call Apple and see if they recommend that as well. There is seriously no reason the Snow Leopard should be causing this problem. I have three other machines in my house running 10.6 that are having absolutely no problems. It just doesn't make any sense at all to me.

 

[Apocrathia]

Well I've got an RMA and a shipping label for my iMac now. Going to drop it by a FedEx/Kinko's tomorrow to get it on it's way back. I was told on the phone that I would be getting a brand new iMac and not another refurb to ensure that I won't continue to have problems.
I am probably going to do full image and a 35-pass wipe of my hard drive tonight before I send it back in.