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Nic T Author

Level 1

0 points

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

I just took delivery of my new iMac 2 days ago.

It's a 2009 2.93GHz, 24" iMac, 4GB RAM with ATI Radeon 4850.

As usual when I take a new delivery, perform a hardware test using the test diagnostic DVD that came with it, checks out fine.

Next, erase the HD and reinstall 10.5.6 from the supplied DVD, applied the updates, then use Disk Utility to check the HD and repair permission, no problems, then after a couple of minutes, the iMac froze. I have nothing connected except for the keyboard and mouse.

Mouse does not move, keyboard does not respond to input. Pressed the power button for 5 secs to shutdown. Booted up in single user mode to repair HD, started up fine again, started to install my apps and move the files over from my previous iMac. Played movies on it, and it froze again. Mouse & keyboard does not respond to input, just a short 1 sec sound from the movie that kept looping.

This happens a few times a day.

Got fed up, reinstalled the OS again, zapped NVRAM, PRAM, Disk Utilities check, repaired permissions, started to play COD4, just a couple of mins into the game, the iMac froze again. Keyboard & mouse will not respond to input, sound stutters.

What's wrong? Any ideas?

2009 Early iMac 2.93GHz, 24" ATI 4850, Mac OS X (10.5.6)

Posted on Apr 15, 2009 11:16 AM

163 replies

Nic T Author

Level 1

0 points

Apr 20, 2009 2:59 AM in response to Sermon

That's 1 good news I have heard so far. Have you tried to play like 4 or 5 HD movies at once, let it loop and run for up to 30 mins, see if it freezes.

Apr 20, 2009 6:22 AM in response to Nic T

I got the freeze aswell. 5 times in 4 days. Can't figure out any pattern except that I have the Imac24" with 4850 Radeon ATi gfx... sounds familiar?

Apr 20, 2009 5:52 PM in response to Nic T

I have installed Fan Control for Intel iMacs, and have not yet had a freeze, although admittedly I haven't taxed the machine much either. I modified the setting of Fan Control to set the upper limit to 70C.

In other news, I received a return authorization from Apple, and am awaiting shipment of a new computer.

Nic T Author

Level 1

0 points

Apr 20, 2009 7:49 PM in response to Nic T

I just got off the phone with Apple Tech Support. I asked if the issue has been fixed because I don't want to receive another iMac with the same issue, go through the whole troubleshooting steps, and then send it back again ... although it is nice to unbox a new Mac.

The good news is, they've identified the issue as ATI 4850 related, the new batch is supposed to have the firmware updated for the graphics card, although ATI has not released the firmware to public.

Fingers crossed.

oracle

Level 2

175 points

Apr 20, 2009 11:12 PM in response to Nic T

Hey there,

I was wondering if anyone has any pblm with OS X Server installed on this iMac ?
Same issues ? freezing ?

Thanks

rosmond

Level 1

0 points

Apr 21, 2009 5:40 AM in response to Nic T

Unboxed my 2.93 4850 Saturday, suffered numerous freezes over the course of the day and Sunday, then noticed that wifi was on, turned it off (I was actually connected to internet via ethernet anyway), no problems since.

Spoke to tech support this morning, and of course as most of the rest of us have experienced it was the first they had heard of it. In fact he was himself sitting in front of a 24" iMac with 4850, and he had wifi ON too.... I passed the urls of the threads here and those at macrumors on to him. It does appear at least that they are taking this seriously, although the guy I talked to was as baffled as the rest of us as to why the 4850 and wifi should combine to produce such a catastrophic problem!

Here's hoping for a resolution soon.

Luba Cox

Level 1

0 points

Apr 21, 2009 6:34 AM in response to Nic T

Hi Nic T, will the new firmware that you mention scale down the performance of the ATI 4850? I hope not, we all got the Radeon 4850 because it is supposed to be better than the GT 130! To think I could of, should of gone into an Apple store instead of waiting and just get the iMac with GT 130 and have no problems. I haven't set up my iMac yet, will later today or tomorrow. Hopefully, I am not one of the unlucky ones, or perhaps all 4850s are affected.

Nic T Author

Level 1

0 points

Apr 21, 2009 6:49 AM in response to Luba Cox

That's a good question Luba. If you still have the unit, maybe you or someone here can do some some of graphics benchmark on it, then when I get my replacement delivered to me tomorrow or the day after, we can compare results.

Any free graphics card benchmarking utility out there?

Nic T Author

Level 1

0 points

Apr 21, 2009 6:56 AM in response to Nic T

Here, can someone run xBench's last 3 tests and post the score?

http://www.macupdate.com/info.php/id/10081/xbench#changesContainer_link

1. Quartz Graphics Test
2. OpenGL Test
3. User Interface Test

Jim Kohn

Level 1

50 points

Apr 21, 2009 8:42 AM in response to Nic T

I just spoke to Apple Tech support. I'm trying to decide if I should cancel my order and wait until there has been a definitive resolution of this issue. Tech support said there is no issue, but I was told by customer service it's no problem to return it if it does not work properly. They pay return shipping, no restocking fee.

It now sounds like people are having some success with a) disabling airport card, and b) installing "fan control". Two questions: does disabling airport card effect heat inside the iMac? Is there anyone who has done both of these things and IS still experiencing the freezing issue?

Apr 21, 2009 9:37 AM in response to Nic T

I'm curious as to how you found out about a firmware update. Apple is normally very close-mouthed about such things. If true, though, it's great news for all of us!

Best of luck.

RzBot

Level 1

0 points

Apr 21, 2009 10:26 AM in response to Nic T

Nic T when is your replacement iMac going to arrive? Let us know the results when it does. Thanks.

rithim

Level 1

25 points

Apr 21, 2009 5:48 PM in response to Nic T

I received my iMac today [2.93 24" with the ATI 4850] and have not experienced any freezing/lockups so far, yay! I am holding off to transfer all my files onto this computer to put it through some more stress tests first, but I tried watching several hd 1080p trailers and no hiccups yet.

I should note that I am using a wired ethernet connection.

Nic T Author

Level 1

0 points

Apr 21, 2009 7:39 PM in response to rithim

Rithim, try turning on your Airport and see if it freezes, thanks.

Nic T Author

Level 1

0 points

Apr 21, 2009 7:41 PM in response to RzBot

RzBot, my replacement is supposed to be delivered by 23rd.

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