Sensor says GPU overheating, but it's not, plus other things

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iMac Intel 20" EMC 2133 and 2210

Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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Andrei @andreipopa

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Postato: 21 gen 2019

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Sensor says GPU overheating, but it's not, plus other things

It’s an iMac 8,1.

Sensor says the GPU is overheating (about 15 - 20 Celsius above what it showed until now) but it’s actually not, it’s actually really cool when you check the back case with your hand.

What might be overheating a bit is the power source, but this is located way above the GPU.

I did not pay attention to the PS temperature, before, so not sure if it is overheating, but it’s the only thing that is warm on the back of the iMac, GPU is cool, SSD is cool.

Ran an apple Hardware test and got this: 4MOT / 1 / 40000003: HDD- 1499

I did a search on that and found this:

iMac Intel 20" EMC 2133 and 2210 Hard Drive Fan Replacement

Why am I getting an Apple Hardware Error 4MOT/1/40000003:HDD-1364

Is there a 3rd HDD fan under the mobo as it seems, but not very well presented in the last 2 steps of the first link?

By the error code above does it mean that the HDD fan under the mobo is failing and that’s why the PS is getting hotter?

Why does the GPU sensor says it’s overheating when it’s not?

One thing I noticed is if the screen gets put to sleep, after a while, the temperature is much lower.

I use iStat, you have a screenshot with the sensors, would TGPro give any other info besides iStat ?

Here are the temps on the "normal setting", you have a screenshot of the fan speeds at that setting as well.

Another thing that is weird is if I crank the fans does not seem to make much of a difference on the GPU temperature, unless it's 90 Celsius or so, bringing it down to about 80.

Cranking the fans makes a big difference on all other components.

So basically, GPU just sits at 80 no matter what fan speed, if I open multiple youtube windows it goes to 90, and will come back to around 80 if fans are cranked.

Here you TG Pro

The readings

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TG Pro offers a bit more info iStat doesn't.

As an example a high water mark on the bar graph so we can see how hot it got, The full version also offers logging so you can plot out over time what has happened.

In any case, visually you can also see things just better comparing the sensors outputs.

22 gen 2019 da Dan

You have the TG Pro screenshot in the original question, so odd this site does not let you post pictures in replies...

22 gen 2019 da Andrei

Now let it run for a few days so we can watch the high water line on the different GPU sensors so far the Diode sensor is on the high side (this sensor is within the GPU)

22 gen 2019 da Dan

Hi @danj you have the reading as requested as an update to the original question

24 gen 2019 da Andrei

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TG Pro offers a bit more info iStat doesn't.

As an example a high water mark on the bar graph so we can see how hot it got, The full version also offers logging so you can plot out over time what has happened.

In any case, visually you can also see things just better comparing the sensors outputs. — Dan
You have the TG Pro screenshot in the original question, so odd this site does not let you post pictures in replies... — Andrei
Now let it run for a few days so we can watch the high water line on the different GPU sensors so far the Diode sensor is on the high side (this sensor is within the GPU) — Dan
Hi @danj you have the reading as requested as an update to the original question — Andrei

mayer @mayer Rep: 685,3k MacHale Enterprises 3,4k 1,1k 2,6k · Answer 1 · 2019-01-21T08:28:13-07:00

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mayer @mayer

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Postato: 21 gen 2019

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I would first check to see if the hard drive sensor is correctly attached to your hard drive (it is just stuck on there) and that the sensor cable is fully inserted into the logic board. See steps #13 & 14 of this guide:

Sostituzione disco fisso nell'iMac Intel EMC 2133 o EMC 2210 da 20"

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HDD has been replaced with SSD a long time ago, the HDD sensor has not been a problem since, nor has the HDD fan. As for the sensor itself it just sits there next to the SSD frame.

22 gen 2019 da Andrei

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Dan @danj Rep: 479,3k Self employed contract worker 35 329 971 · Answer 2 · 2019-01-21T08:39:46-07:00

To start with the temp at the GPU is not the same as what you would feel on the external case. Think of it this way… Your oven is maybe warm to the touch but the you won’t touch the heating element inside!

Lets backup here as you told us how much higher the temp went but you didn’t tell us the start point: “Sensor says the GPU is overheating (about 15 - 20 Celsius above what it showed until now)” Can you tell us how you measured this and if this was just one time jump. If it’s happening more often what are you doing when it happens.

The AHT error 4MOT / 1 / 40000003: HDD- 1499 is telling us the hard drive fan has failed. So you do need to replace it following the guide you’ve already found. The HDD fan is mounted under the logic board which is why you need to lift it off. There are three fans in this system: CPU/GPU, HDD & ODD.

As for why the power supply is getting hot and why you have a hot GPU will need further investigation. How about installing a good thermal monitoring app like TG Pro so you can see more effectively whats happening and when. Post a snapshot of the main window showing all of the sensors so we can see things too Aggiungere immagini ad una domanda

It also sounds like you’ve done a bit of work in your system how about given us some history what you’ve done. I would also recommend you check your connections in case you reversed one (sensor or fan) as they are located next to each other and look the same.

At this point I don’t seen anything with the GPU other than the diode sensor. I would dust the system out fully and clean both the CPU & GPU of the old thermal paste and pads and putting fresh paste and pads on. Given the systems age I think thats all thats required here.

GPU not the same as you feel on the case.

Sure, but the GPU part of the case is downright cold, while the PS part of the case is warm.

I also opened the iMac to try to find what is going on and clean it, and all the other parts were pretty much cooled down ( it must have taken just minutes to open it ) while the PS was still quite warm.

How I measured it and one time jump.

I did not pay too much attention to the GPU temperature, but to the CPU temperature, about two weeks ago randomly I felt with my hand that the back of the iMac was quite warm, so I checked the temperatures.

I noticed the GPU was around 80 Celsius. As I said, my focus usually is CPU, but I don't think the GPU would run that high, more like 60-65, under 70.

This has not happened before and just started out of the sudden about 2 weeks ago, and it's constant since it started.

Nothing specific happened at the time, and no heavy resource software was running.

The computer just does normal browsing stuff, nothing out of the ordinary.

See continuation and screenshot below, as it did not fit in one comment. — Andrei

iMac Intel 20" EMC 2133 and 2210

Sensor says GPU overheating, but it's not, plus other things

Update (01/22/2019)

Update (01/22/2019)

Update (01/24/2019)

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Update (01/24/2019)

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