CPU throttled in 2014 iMac

[InfoTime]

I've got an iMac (21.5-inch, Mid 2014) that I'm to resurrect. It belonged to my mother in law. She got rid of it a couple of years ago as it was running really slow.

I figured the first problem was having a stupid spinning hard drive in there. So I popped in a 2.5 inch SSD. That SSD already had a working Windows 10 install from an old Dell. Surprisingly it booted and ran that Windows install. But it was also slow.

I think the CPU is being throttled. Windows system information reports the CPU model as an Intel(R) Core(TM) i5-4260U CPU @ 1.40GHz 2.00 GHz. However, Task Manager shows the CPU speed at 0.79 GHz.

The fans are running slightly elevated. They ran slightly elevated with the stock hard drive running Mac OS.

Any suggestion as to what's wrong?

 

[theorist9]

You're running an original Widows OS directly on a Mac, rather than running it on a specially-prepared Bootcamp partition. Since Macs aren't designed to do this, that could be the problem.

I would start by doing things the officially-supported way--boot into internet recovery, erase the drive (since it's an SSD you don't do a secure erase--just a regular erase is the ticket), reformat for MacOS, install MacOS, and then see how it runs. If you want to run Windows, then either use Bootcamp or buy Parallels.

 

[InfoTime]

Makes sense. I don't really care about running Windows on this machine. I just let it boot on a lark, since I had that spare SSD lying around. I ran a program called HWiNFO64 and it confirms the clock speed of 800MHz. I thought I'd find a high temperature but it's reporting 33C.

I get that I'm not running Windows correctly and that may be the issue. But I find it interesting that the fan noise and the sluggishness seemed the same under Mac OS.

I'll go ahead and do a proper macOS install and see how it goes.

 

[InfoTime]

Mods please move this back, I'm not really troubleshooting Windows, I'm installing macOS as I type this. I think I have a hardware problem with my Mac.

 

[InfoTime]

I would start by doing things the officially-supported way--boot into internet recovery, erase the drive (since it's an SSD you don't do a secure erase--just a regular erase is the ticket), reformat for MacOS, install MacOS, and then see how it runs.

I did all that. After booting into recovery, formatting the drive and launching the installation I checked the clock. From the point where the actual install started until I could log in as a user was about 4 hours. The clean install of Big Sur is dragging. The fans are spinning. Behaving just like it did with the old spinner, the new SSD with Windows and now the new SSD with a clean Mac OS install.

Unless someone can convince me otherwise, it's a hardware problem. The question is: what's causing it? And, is there a simple fix.

 

[theorist9]

Now that you've got a proper clean install, the next steps would be to do an SMC reset and a PRAM reset, and then do an Apple Hardware Test. You might also try booting into Safe Mode, though since you're operating on a clean install I don't know if that would have any effect.

 

[Bigwaff]

When you are logged in, install software which will monitor internal temperature sensors. I assume when you replaced the HHD with SSD you blew out all the dust, etc. I’d open it up and retrace my SSD install steps. Inspect the boards for corrosion. I suspect a thermal sensor isn’t connected or has failed.

 

[genexx]

I am guessing that analogue to the iMac+s 27 of this time, a temperature Sensor for the SATA conected HD/SSD was needet to Report the Temperature of the SSD/HD and thus not reporting a Temperature throtteling the CPU.

iMac Intel 21.5" and 27" (Late 2012-Early 2019) SSD Temperature Sensor

Add an SSD to your iMac with this cable. A temperature sensor for the SSD is included.

www.ifixit.com

I have developed a solution that eliminates the error problem 4SNS/1/40000000: TH00-9.000 after replacing the hard disk in the following Apple models that do not have an external drive temperature sensor:
- iMac 21.5" A1311 (2011 model)
- iMac 27-inch A1312 (2011 model)
- iMac 21.5" Retina A1418 (models 2012, 2013, 2014, 2015)
- iMac 27" Retina A1419 (models: 2012, 2013, 2014, 2015)

My method requires no investment in adapters, additional cables or modules, does not interfere with the computer's wiring, is fast and 100% effective. It resolves all the symptoms described below, including the error display in the AHT.

Symptoms:

- Very slow operating system,
- Kernel task 100% and more in the Activity Monitor (constant, full CPU load),
- high fan speed (hard disk fan on A1311/A1312 models, main fan on A1418/A1419 models),
- 4SNS/1/40000000 error: TH00-9,000 in the AHT (Apple Hardware Test - triggered by holding the Alt+D keys during the boot process).

Cause:

New hard disks that do not bear the Apple logo are not compatible with the SATA standard introduced by Apple, which provides for a temperature sensor on the drive's electronic board. Apple drives use pin 11 of the SATA power connector (15-pin) to transmit the voltage from the temperature sensor. The difference between the standard SATA connector and Apple's SATA connector is explained below:


Figures 1 and 2 - Pin assignment of the SATA power connector (standard pin assignment on the left, Apple pin assignment on the right)

Solution:

Simply connect pin 11 to pin 12 of the SATA power connector with a drop of tin before installing the drive, as shown in the figures below:

Fig. 3 and 4 - Connection of pins 11 and 12 of the SATA connector (on the left a 2.5" drive, where the solder joints of the connector are accessible without removing the electronics, on the right a 3.5" drive, where the solder joints are inaccessible from the outside and the electronics board must be removed)

 

[Boyd01]

Mods please move this back, I'm not really troubleshooting Windows

Moderator Note: Thread has been moved to the iMac forum, but it's not clear to me if this is where you want it. We're happy to move threads, but it's better to use the report button for the first post and tell us where you'd like it moved instead of posting to the thread. Thanks!

 

[InfoTime]

a temperature Sensor for the SATA conected HD/SSD was needet to Report the Temperature of the SSD/HD and thus not reporting a Temperature throtteling the CPU.

I observed the same slow CPU symptoms with the stock Apple hard drive before I ever opened up the system. If your theory is correct (which I'm not doubting or challenging) then I guess the stock hard drive might have had a defective sensor too, which would explain the effect both before and after surgery.

 

[genexx]

I observed the same slow CPU symptoms with the stock Apple hard drive before I ever opened up the system. If your theory is correct (which I'm not doubting or challenging) then I guess the stock hard drive might have had a defective sensor too, which would explain the effect both before and after surgery.

Possible, but I do not know exactly because i never owned - iMac 21.5" Retina A1418 (models 2012, 2013, 2014, 2015)

You can also check with Apple Hardware Test - triggered by holding the Alt+D keys during the boot process....

Symptoms:

- Very slow operating system,
- Kernel task 100% and more in the Activity Monitor (constant, full CPU load),
- high fan speed (hard disk fan on A1311/A1312 models, main fan on A1418/A1419 models),
- 4SNS/1/40000000 error: TH00-9,000 in the AHT (Apple Hardware Test - triggered by holding the Alt+D keys during the boot process).

This is a very common issue with 27" iMac Models.

 

[InfoTime]

You can also check with Apple Hardware Test - triggered by holding the Alt+D keys during the boot process....

There may be an issue with the System Management Controller (SMC)
Reference Code: PFM006

 

[genexx]

If you are lucky you only have to change the little PRAM Battery........
If not ......

But it seems you have to literally detach every piece of the 2014 iMac....

 

[InfoTime]

Interesting. Correct me if I'm wrong, but to get to the battery to replace, I have basically tear the system all the way down and remove the logic board to get to it?

iMac Intel 21.5" EMC 2805 PRAM Battery Replacement

Use this guide to remove the PRAM battery.

www.ifixit.com

 

[genexx]

Interesting. Correct me if I'm wrong, but to get to the battery to replace, I have basically tear the system all the way down and remove the logic board to get to it?

iMac Intel 21.5" EMC 2805 PRAM Battery Replacement

Use this guide to remove the PRAM battery.

www.ifixit.com

That is what iFixIt tells.... i do not have an iMac 2014 21....
The chance that the SMC is really defective is still very high.

 

[GrumpyDonkey]

You're running an original Widows OS directly on a Mac, rather than running it on a specially-prepared Bootcamp partition. Since Macs aren't designed to do this, that could be the problem.

I would start by doing things the officially-supported way--boot into internet recovery, erase the drive (since it's an SSD you don't do a secure erase--just a regular erase is the ticket), reformat for MacOS, install MacOS, and then see how it runs. If you want to run Windows, then either use Bootcamp or buy Parallels.

Running Windows directly without the terrible BootCamp support files will not slow a machine down. If anything it should be faster.

If you really need it, find the download link on the Apple website for the latest version of BootCamp. Only install it on the windows side. BootCamp when used from Mac OS was a terrible abomination of software.

 

[genexx]

Have you tryed reset the SMC ?

How do you reset the SMC on a 2014 iMac?


iMac, Mac Mini, or Mac Pro

1. Shut down your Mac.
2. Press and hold the power button for 10 seconds, then release the button.
3. Wait a few seconds and restart your Mac.
4. If that doesn't help, shut down your Mac again.
5. Unplug the power cord and wait 15 seconds.
6. Reconnect the power cord and wait 5 seconds.

 

[Fishrrman]

If it was me, and if I had a 10-year-old iMac I wanted to keep alive and squeeze better performance from, I'd just erase the internal drive, leave it "in place, where it lies", and add a USB3 external SSD to become the new boot drive.

Cheap, fast, easy and less chance of breaking anything inside.

When it's time to retire the iMac, just disconnect the SSD and take it to the new Mac...

 

[genexx]

Makes sense. I don't really care about running Windows on this machine. I just let it boot on a lark, since I had that spare SSD lying around. I ran a program called HWiNFO64 and it confirms the clock speed of 800MHz. I thought I'd find a high temperature but it's reporting 33C.

to @GrumpyDonkey and @Fishrrman

please read the Thread before making useless recomendations

The SMC seems to be broken - Hardware Test put out Reference Code: PFM006 - we tried to figure out what makes it a lame Duck running 800Mhz CPU.........

There may be an issue with the System Management Controller (SMC)
Reference Code: PFM006

 

[InfoTime]

iMac, Mac Mini, or Mac Pro

1. Shut down your Mac.
2. Press and hold the power button for 10 seconds, then release the button.
3. Wait a few seconds and restart your Mac.
4. If that doesn't help, shut down your Mac again.
5. Unplug the power cord and wait 15 seconds.
6. Reconnect the power cord and wait 5 seconds.

I did several PRAM resets, but not sure if I've tried holding the power button in for 10 seconds. The machine has also been sitting on a shelf, unplugged for about three years.

 

[macguru9999]

I've got an iMac (21.5-inch, Mid 2014) that I'm to resurrect. It belonged to my mother in law. She got rid of it a couple of years ago as it was running really slow.

I figured the first problem was having a stupid spinning hard drive in there. So I popped in a 2.5 inch SSD. That SSD already had a working Windows 10 install from an old Dell. Surprisingly it booted and ran that Windows install. But it was also slow.

I think the CPU is being throttled. Windows system information reports the CPU model as an Intel(R) Core(TM) i5-4260U CPU @ 1.40GHz 2.00 GHz. However, Task Manager shows the CPU speed at 0.79 GHz.

The fans are running slightly elevated. They ran slightly elevated with the stock hard drive running Mac OS.

Any suggestion as to what's wrong?

that happened to me, i ran an intel utility to diagnose (mac version) and replaced the cpu with a model that originally came with that imac. it now works perfectly to this day