The ultimate iMac 2009 (freezing but mouse moves thread)

[drasl]

I have an iMac late 2009 27” and I am one of the many experiencing random GUI freezing where there is no spinning beach ball or any indication of the freeze until you move the mouse (yes the mouse pointer moves) and try to click something og interact with something.

Music will even continue playing in the background.

There are some threads about this but no one seems to have a solution to what is going on, so I wanted to try to get some brothers in pain to give a little information about their iMac that could possibly help diagnose the problem.

My first thought was having a small list where everyone inputs their specs and modifications of their iMac.

Model: iMac (Mid 2009)
Year: 2009
Screen size: 27"
CPU: 2,66 i5
GPU: ATI Radeon HD 4850 graphics processor with 512
Original HDD in HDD bay ?: No
HDD/SSD in HDD bay: 2TB Seagate HDD
HDD/SSD/DVD in DVD bay?: Samsung EVO 840 SSD
OSX version: Yosemite
Aftemarket memory ?: Yes
Memory in GB: 6GB
Do you use bootcamp: Yes
Graphic intensive gaming in bootcamp ?: Yes sometimes.

If you replaced the HDD did you need a fix for the fan speed and if so what method (short the wire, fan control software, OWC HDD sensor , other ?):
I used: Fan control software

 

[drasl]

I noticed that the fan never revs up when using bootcamp after replacing the HDD and using a software based solution to control the fan speed.

Even when the computer obviously got very hot.

I stopped using bootcamp after I noticed the overheating issue, but my theory is that it might have overheated the GPU as well , and possibly related to the screen freeze issue I am experiencing.

 

[MrNomNoms]

I noticed that the fan never revs up when using bootcamp after replacing the HDD and using a software based solution to control the fan speed.

Even when the computer obviously got very hot.

I stopped using bootcamp after I noticed the overheating issue, but my theory is that it might have overheated the GPU as well , and possibly related to the screen freeze issue I am experiencing.

My sister experienced the same problems and I hazard to guess that the machine is clogged up with dust. if you're adventurous I guess you could clean it yourself by pulling it apart but there are repair agents who could probably do it for you.

 

[drasl]

I decided to check inside the computer and check how the computer was inside as you suggested.

Since I was opening it, I decided to buy a Seagate HDD with a compatible temperature sensor, so I could stop using the HDD fan control software to regulate the fan speed.

Not a lot of dust, and the new Seagate works perfectly and now the iMac runs with normal fan speed without the need for hdd fan control.

But there is one more thing......I found a crushed wire where I had fastened the HDD originally when I moved from 1tb to 2tb drive.

The cable had the wires exposed but was not completely severed and was making contact with the HDD hardware, I followed the wire and found its connected to a unit that controls the LED backlight.

I moved and insulated the wire and assembled the iMac again.

Im not sure a wire to the LED backlight unit could cause the freezes, but unfortunately if the problem stops appearing, I won't know if it was the HDD fan software (and the HDD drive that did not talk to the heat sensor) or the crushed cable.

Perhaps neither of them, and I still have the problem, time will tell.

 

[drasl]

Well not a single "freeze" event since I replaced the HDD, and used a HDD that the iMac can read the temperature on, as well as moving the crushed LED backlight wire from the HDD assembly.

Unfortunately since there were two fixes performed I can't isolate the cause of the crashing, but many 27" 2009 iMac users have been complaining about similar issues.