2009 Early iMac Freezing 2.93GHz,24", ATI 4850

I have about the same story! After using few days my new iMac I had already gotten couple freezing situations. Once I felt that the cap where the cooling air is coming out was really hot, almost "burning". I and my son were wondering that but then forgot it.

After these freezing mainly when using GarageBand or iPhoto loaded Derman's iMac Fan Control. After that I have had no freezing. I made one test: dvd playing movie, iTunes playing music, youtube playing, heavy iPhoto operation, all at the same time. No freezing and desired/current fan speeds and temperatures were (thresholds set to 30/90 C, all lowest fan speed values as minimum):

CPU 1400/1800, <40 C
HD 2200/2200, 45 C
DVD 1300/1300, <40 C
GPU 48 C (no fan)
Room temperature 23 C

I measured also the temperature of the cooling air gap with infrared meter and it was 47C. Feeling with hand was that it was much cooler than earlier. Anyway about what you expect from a running computer.

I feel relieved because even apple people we recommending to use the Derman program (?). So it can not be disaster to my iMac. It was loaded deep into the system (not a normal program) and I don't know how to remove it anymore. So far there seems not to be any problems, only positive things, and if this continues I will keep it. I have asked from Derman company this instruction and am hoping to get it later (for to feel myself more comfortable).

Juha,

If you DID want to uninstall fan control, follow the follow steps:

1. Delete 'imac fan control' or 'fan control' as described, deleting the daemon + pref. pane in the library folder (this is found Library -> PreferencePanes ->)
2. Restart. Now empty the trash can (that couldn't be deleted because files were being used). Restart again.
3. After a clean restart, once at the desktop, perform a SMC reset; You'll hear a long beep that'll confirm.
4. Perform a PRAM reset as you boot up. Do this at least twice, for a total of 3 startup beeps.
5. Confirm with iStat widget that fans follow factory setting RPMs.

...I found these instructions by following a link from the Derman site. They worked for me. My theory here is that post-EFI firmware update, I'm going to run my Mac as Apple intended it to. Hopefully this should mean things go problem free...

Martin,

thank you. I will follow you if needed. By the way, have you used the same iMac Fan Control?

Juha,

Yes - I believe I had installed the very same program, available at:

http://www.derman.com/Download/Special/iMacFanControl.html

While the program successfully reduced my operating temperatures, it did not fix the freezing, which was related to wifi problems. The new firmware fix seems to have eliminated the freezing.

Best regards,
Martin

Martin,

ok. I do have WLAN internet (or Wi-Fi?) but recently I have had LAN cable connected. What firmware fix did you have and from where I can get that?

Best regards
Juha

Hi Juha,

If you check Software Update it should show up there, otherwise you can download it from the following link:

http://support.apple.com/downloads/iMac_EFI_Firmware_Update_14

It is called "Mac EFI Firmware Update 1.4".

Good luck - and follow the instructions explicitly.

Not a single freeze with wifi enabled and under heavy use since Saturday evening. I love my Mac!

Its Here!!!!!!!!


This update fixes intermittent system freeze issues for iMac computers with ATI Radeon HD 4850 graphics and fixes wake-from-sleep issues in Boot Camp.

To complete the firmware update process, please follow the instructions in the updater application (/Applications/Utilities/iMac EFI Firmware Update.app). The updater will launch automatically when the Installer closes.

btw..... my nvidia 512 stoped freezing after turnning off time machine! Reinstalled os x first and it froze right away, turned of time machine and it is running fast with no lock ups !!!!!

In event anyone did not get the firmware update here from Software update, and has an ATI 4850, it has been released online too:

http://support.apple.com/downloads/iMac_EFI_Firmware_Update_14

Did you have only this one freez since FW update?

I see that nobody else complaining since FW update so problem is definitely fixed ?? (I am thinking of upgrading to iMac with 4850...)