iMac (i3 2010) random freezing and now with 3 beeps

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Level 1

5 points

iMac (i3 2010) random freezing and now with 3 beeps

Hi I have a 21" iMac i3 base model with 8Gb of Ram (see below).

Ever since I got the mac about 10 months ago it has been randomly freezing up, becoming completely unresponsive to any input (keyboard mice etc), and can only be fixed by a hard reboot (holding down power button).

It can happen while I am away at lunch and I come back to find it frozen on the screen saver. Other times I'm just browsing the web (nb has happens with safari, firefox, and chrome). While others times I have been using the system to its fullest. There never seems to be a reproducible way of triggering it. I can go for a week without issue, and then it can happen 6+ times a day, and they go back to being fine again for awhile. Although it has been getting progressively worse over time and more constant.

I have tried repairing permissions (disk utility and onyx). Defraged the drive (drive genius), run TechTools pro and it passed all the tests. I don't have access to the orginal disks (work iMac) so running the AHT is not possible, as is a clean instal.

I updated to 10.6.8 this week, and now when it freezes, it is now accopained by 3 loud beeps...pause...3 beeps etc etc.

This suggests that it could be a memory problem, but I have never had a problem during the boot up process, and as I said it has passed the memory test on both TechTools6 and Rember, I'm not sure if this is the case.

Because the system completely frezzes, there is no log or error reports created, meaning that pin-pointing the issue or even having proof for the tech-guys/Apple is difficult.

Has anyone got any suggestions on a fix, or how I might be able to get an error report, or how I could induce the problem on que.

Thanks heaps

a

Model Name: iMac

Model Identifier: iMac11,2

Processor Name: Intel Core i3

Processor Speed: 3.06 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache (per core): 256 KB

L3 Cache: 4 MB

Memory: 8 GB

Processor Interconnect Speed: 5.86 GT/s

Boot ROM Version: IM112.0057.B00

SMC Version (system): 1.64f5

Posted on Jul 13, 2011 5:19 AM

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Answer 1

louie

Level 4

2,950 points

Jul 13, 2011 6:58 AM in response to Underpantman

You do seem to have the symptoms of bad RAM. According to Apple, it is possible for bad RAM to pass the power-on test, yet still be bad:

http://support.apple.com/kb/HT2341

I'd try reseating the RAM, then changing the RAM, then considering warranty repairs for what could be any number of other problems, such as a bad main board or hard drive. If it freezes that much, it should be incumbent on the tech-guys to take your word for it and fix it.

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Answer 2

Underpantman Author

Level 1

5 points

Jul 13, 2011 7:35 AM in response to louie

Will try reseating the RAM as suggested. Unfortunately I seem to know more about Macs then the tech guys here. Fortunately it crashed just before, and I was able to get hold of one of them to show them... so at least they believe me now 🙂

Thank for the help

a

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Answer 3

Underpantman Author

Level 1

5 points

Jul 18, 2011 4:55 AM in response to Underpantman

Ok so it definitely appears to be the RAM. I have found a way to reproduce the crashing....Running Prime95. Its normally takes about 15-30min on the stresstest to get the system to lock up.

But here is the strange thing. It only seems to work if I have the full 8Gb installed.

I have run each 2Gb stick by itself without issues.

And then run 6Gb, changing the empty slot each time, and again no crashing.

I found the following thread also has similar issues, with the RAM the most likely cause.

https://discussions.apple.com/thread/3175303?answerId=15610565022#15610565022

I can discount USB,wifi,bluetooth as I tried this and still managed to get a crash.
But I did have screen sharing on so I am now testing if I can run the 8Gb with this disabled.

Will report back with my findings.

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Answer 4

Underpantman Author

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5 points

Jul 18, 2011 5:04 AM in response to Underpantman

🙂

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Answer 5

Underpantman Author

Level 1

5 points

Jul 18, 2011 7:20 AM in response to Underpantman

Screen sharing had no effect. 8Gb still crashes it after about 15min of Prime95.

Does this mean that the motherboard or logic board is faulty?
Should I bother replacing it or just get by with 6Gb of RAM?

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Answer 6

louie

Level 4

2,950 points

Jul 18, 2011 8:35 AM in response to Underpantman

I do not know. Your test does not seem to pinpoint a bad slot, or bad RAM stick. Since you should be under warranty, and you can reproduce the freeze, I think I would take it to Apple for repair, as I would prefer to have the issue resolved under warranty rather than using 6GB.

However, if you have the patience, I would try replacing all the RAM, or at least any non-Apple RAM. Non-Apple original RAM is the first thing they will question.

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Answer 7

accocan

Level 1

0 points

Aug 20, 2011 11:41 AM in response to Underpantman

I have exactly the same iMac model and exactly the same problems after installing 2*2GB Kingston DIMMs (KTA-MB1333/2G). The Apple hardware test doesn't report a memory problem neither does memtest86. Tested with DIMMs in different slots and with OSX 10.6.7, 10.6.8 and 10.7. After removing the two Kingstons everything has been fine for several days now.

I have now ordered 2*2GB Corsair DIMMs (CMSO4GX3M2A1333C9), I'll let you now what the results are.

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Answer 8

Underpantman Author

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5 points

Aug 22, 2011 4:35 AM in response to accocan

I hope that this fixes it for you although in my case, each DIMM was by its self ok. It was only when I had the full 8Gb installed that I would get crashes. I am now running on 6Gb and haven't had a crash in weeks, nor is Prime95 able to crash the system.

a

🙂

ps I upgraded to Lion and re-did the tests, and it still crashes with 8Gb installed. The only difference is the beeps are now super super loud, rather than just plain loud. Nearby co-workers thought it was a fire alarm lol

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Answer 9

accocan

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Aug 22, 2011 10:30 AM in response to Underpantman

Haven't tried using only 3 slots yet, but I might give it a try. It'll be a week or so before I get the new DIMMs anyway.

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Answer 10

Aug 30, 2011 3:36 PM in response to Underpantman

I'm have the same problem, will remove my extra RAM and see what happens. @accocan have you got your new RAMs yet? Please let us know how it works out.

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Answer 11

accocan

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Sep 1, 2011 1:55 PM in response to Storbastan

I added the Corsair RAM some three hours ago, so it's still early days, but no freeze sofar. I'll keep you up to date though.

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Answer 12

accocan

Level 1

0 points

Sep 3, 2011 2:36 AM in response to accocan

39 hours after adding the Corsair RAM (at a cost of 30 USD) and still no freezing! This seems to have solved my problems! 😀

I've now had Elgato EyeTv running live TV constantly, with Caffeine preventing the iMac going into sleep mode (with normal use on the side: browsing, reading mail, doing video encoding). This has allways caused freezing before, in between 10 min to 10 hours. I've been trying to solve this problem for the last 4 months, updating EyeTv, the Elgato hw, OS-X, but it kept freezing/beeping, now and then also without EyeTv running.

As I said, swapping memory slots has had no effect and memory test programs haven't reported any problems, but as it turned out, this seems to be a memory compability problem after all. What memory are you using?

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Answer 13

accocan

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Sep 4, 2011 3:54 AM in response to accocan

I think I can stop testing and just start using my iMac normally, no problems during the first 64 hours of continuous use 😀

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Answer 14

Underpantman Author

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5 points

Sep 6, 2011 3:11 AM in response to accocan

I'm glad that things seem to be fixed with your new RAM. I have the official ram from apple (hynix). The only way I could reliably get crashes was using Prime95, so if you really want to be sure I would run that rather then your other tests. I could go for a week or two with no problems then bam 6 crashes in one day.
I tried doing other tests like running HDmovie on loop, with benchmarking software going, compressing movie etc.

Nothing was reliable except Prime95.

a

ps its been over 1 month now with no crashes on 6Gb.

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Answer 15

Dec 16, 2011 6:33 AM in response to Underpantman

I have been having the exact same problem with my 2010 iMac with 8GB RAM. The 8GB of ram were installed by Apple as it was ordered online that way - brand new. This happens very randomly - once every 2 weeks or so, and it does not happen with any specific program. I notice it more when I have more than a few programs open at once. All of a sudden, my entire computer freezes and I hear 3 very loud beeps (like an alarm). The beeps continue until I unlplug the power to the computer. It's the only way to stop it and restart the computer. Then after bootup sometimes it acts slow and sometimes it boots up as normal and everything is fine again. VERY frustrating. Also, it doesn't really FEEL like it should with 8GB RAM. Seems like my computer would run much faster with that much RAM. I believe this issue might be bad RAM like the other ones are. I also read somewhere that 3 beeps can signify bad RAM or poorly installed RAM.

I called Apple Support a while ago about this and the woman on the phone walked me through the typical empty cache/memory reset at startup and said that it shouldn't happen again. She was wrong. It keeps happening randomly just as it always has. During one of the recent episodes, I got my iPhone and recorded the freezing and beeping so that if/when I needed to actually take it in I could show them and they would believe me.

It will be very hard for me to take this in to send it for repair because I work from home and own no other computer, so the time I am out of a computer will mean no pay at all for me and I cannot afford that. 😟 I am also concerned about opening up the computer and checking the memory on my own because I tried to do that with my older iMac and it was so hard to remove/insert the memory that I thought I almost broke it. Way too risky for me to try. I thought about lugging it all the way to the Genius bar to see what they say, but I more than likely will not be able to recreate the issue and they may just tell me to send it for repair which I absolutely cannot do because I can't be without a computer.

So here I am. This pesky problem continues and I am just living with it until I get brave enough to mess with the RAM myself. 😟

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