27-inch / 27" iMac Random Shut down

Hi Folks,

These posts and several other thread's on this subject helped me a great bit.

I recently purchased a mid 2010 27 inch iMac used. When it arrived I noted that it only showed 8GB RAM but I had purchased it as having 16GB. Looked into that and 8GB where disconnected.

I pushed them back in and a day or so later my shut down issues started. I did not suspect the RAM at that point. Installed some fan controls and suspected over heating.

After a lot of searching I did trace it down to added RAM being not compatible and since all of the 2010 wher shipped just with 8GB RAM, the added RAM caused the problem.

Found a post that pointed to a must use of Hynix RAM. So I did order a full set of Hynix. The verdict on these is still out waiting on them to come in.

In the meantime I disconnected the right two chips again and since running just with 8GB again I had no more shut down problems.

Just wanted to pass that on for folks that search this thread or link.

Thanks all of you.

Wolfgang

You might be on to something. I had the same issue with mismatched ram. Now I have 16gb of Samsung which was the original. It seems to be working well. Very few crashes. It seems to happen with Itunes. i have been running it now without Itunes for 2 weeks and there have been no issues.

Icedg,

Is this fix still working? Are you running 16GB as well?

Thanks for the update,

Paul

Hello,

I was a having the crashing problem about a year ago. I replaced the RAM with the 16GB of OEM Samsung RAM and it has not crashed in since. Works perfect.

Hi, Wolfgang again.

I can run this down for you again, I purchased my 2010, 27 inch iMac about 2 months ago. It came with 16GB RAM, they where NewerTech nuRAM, four 4GB modules.

I noted that two chips where disconnected and pushed them back in and almost at once my problem started.

The iMac would shut down without warning, the console did give not any clues and I started scanning the forums.

I did not put two and two together and installed all kinds of monitors, fan controls to no avail.

It still shut down 1-4 times a day.

Than I found a post where a guy stated about four, fife times to install Hynix modules, I searched some more and found some more about the original Apple modules also working, I believe they are Samsung.

I ordered 16GB of Hynix no trouble since. It also ran fine on just two 4GB modules while I was waiting on the Hynix.

Conclusion the mid 2010 27 inch iMac does not like 16GB other than Samsung or Hynix.

Wolfgang

I'm having this problem with my 2013 imac... it was about 12 months old when the problem started; frustrated sent it in to the Apple store twice and they said they could not replicate the problem. Took it back home was fine for the first couple of weeks then started to shutdown without warning again and taking a few minutes and unplugging from the wall to reboot again...

Strangely there also seemed to be distortion of the bass in the speakers near where the power button is .. i got the speakers replaced but the shutdown problem continued.

Really unhappy I need this comp for my work and I can't afford a new one .. I really love Apple but this has really pushed me away.

i've had it twice and after around with the memory mods it came down to a new power supply. Apple knows it has a truckload of bad power supplies in many machines and continues to pretend the problem doesn't exist. It amazes me that the apple techs can look you in the eye and pretend like they've never heard of the problem before.

Now if they'd just fess up to the bad air circulation in a lot of iMacs that gets dust right on the LCD, I would be very happy. Cleaning screens is a nightmare and they sure dont want to address the basic design flaw that deposits the dust in the first place.

<Edited by Host>

Actually, it just occurred to me that the bad air circulation could be affecting both the screen and the power supplies or memory mods -- it's really fine dust particles involved. hmm.

What specific model do you guys have? I had the older unit that was thicker and with the newer units they sure have addressed the "heat" issue because if you go into any Apple Store or BB and touch the back of one of the newer units there is barely any heat from the new ones and they been running all day long. Now on the older units, my died several times the 4 time they finally gave me a full credit and I took that money and bought a Mac Mini and waited till the newer units came out. I been happy so far as my late 2012 unit seems to run perfectly with zero heat or dust issues. But frankly after this one is done, I am going back to a Mac Pro or a Amped up Mini, depending on my needs at the time.

I have a hot one, a 2011 21.5-inch iMac, 12,1, i5 with 8 gigs. I think most of the heat reduction and slimming comes from solid state drives, which undoubtedly called for changes in internal circulation, not so much forced air from fans pushing dust around, and perhaps better sealed screens and power units.

Solution:

Stop paying for over priced PCs and build your own for half the price.

Problem can be overheating, bad ram or bad Firmware. But what Apple really wants you to do is buy a new one.

Using Samsung RAM, exactly as the brand/type issued with the iMac, resolved my power issues.

I will buy another "over-priced PC" anytime from Apple, but would consider buying it with maxed-out RAM to start.

Peace.

funny, i had 4 4gb modules of hynix ram when the problems (sudden shutdowns) started; took out 2 modules and the problem is gone, so in my case hynix was part of the problem; i am now replacing these 2 hynix modules with original samsung modules of 2 gb, i am pretty confident that my imac will keep working with 2x 4 gb hynix and 2x 2 gb of samsung 🙂

Yep... had read your response some time back and finally brought mine into the Apple store. Power supply was bad. The "genius" had seen this issue before but there were not enough officially reported to created a recall. A joke...but at least a $100 fix seems to have done the trick.

Figured I'd join the club here...

I have a late model 2012 27" iMac and a few days ago it started having exactly the same issue everyone here is describing...

It shuts down every 2 to 3 hours..... and if I remove the power completely for a few minutes, usually it will restart again.

Apple telephone support was a joke, As others have mentioned, "Reinstall the OSX", Partion the drive, seriously?

It doesn't look like heat, as I have cranked the fans up, and the temp is below the norm, and it still flakes out.

So hopefully, the genius bar down the street will be able to tell me something worth while, but I can't get it to them for 3 days