My iMac has been turning off repeateadly in the middle of a job. When it does it, I cannot turn it on again inmediately. I have to wait to next day, some times even longer. If the cable is plugged in, I cannot turned it on. I've tried everything. Changing the cable, changing the power font, etc. Some people say the problem is with the mother board. As a consequence of this, my disk drive didn't work anymore.
I have been told this is a factory problem and that Apple is recognizing it. Does anyone know abot it?
Thank in advance
This just happened to one of our new iMacs at my lab. it's been out of the box for a week. I haven't added anything to it. I'll wait a few hours then try it again. Funny thing this one, it was a replacement for an iMac with fan issues. Maybe I'll be replacing the replacement.
Im surprised no one has mentioned software issues because thats what apple care is now telling me.
I have replaced powersupply ,reset smc,pram and run extended ram tests plus used memtest. I have to do a reformat and clean install for applecare to take this any further. 110 day old 27"imac i7
It started with shutting off every 4 days to every three minutes and then lasted a day after a system reinstall then lasted 4 days before shutting off again..the saga continues...
What exactly did the Apple tech tell you when they said it was a software problem? My Apple tech said it's most likely a faulty power supply. I've sent my iMac in for repair, they couldn't figure out what was causing the shutdowns but changed the power supply unit just in case. Fresh from repair, it still shuts down. I called them, and they implied that it's probably some power surge in my building. I had electricians check my apartment, no problem found.
The shop (Macnificos, Spain) where I bought 4 modules of 4 GB of Ram that causes random shutdowns on my iMac 27, has been in contact with the distributor and manufacturer of CSX Ram because some other clients experienced the same problem.
They affirm that shutdown problem is an electric problem of iMac, not a problem of Ram modules, and they are sure that can ocurr when the machine has 16 GB of Ram installed and with some specific modules. CSX can't found any problem on their modules, so they think their RAM is OK, and assure that the problem is random and also can ocurr with Samsung RAM. They think perhaps my modules are defective. I'm not agree with this explanation.
They accept to change my four 4GB modules of CSX RAM with four new identical modules. I will try it all next week, and I will warn you if the problems persist with the new modules, but I'm sure that shutdowns will be continued ocurring because the modules that they're sending to me are identical to that already I have.
Received today 4 new modules of 4 GB CSX RAM. Same problem, after installing, random shutdowns.
So, no defective RAM, sure incompatibility Issues.
With 12 GB, 8 GB (2 modules) or 4 GB (1 module) no problem. With 16 GB, impossible to work.
Waiting a response from the shop for the possibility to change this RAM and get Samsung which does not produce shutdowns according to report several users.
As I've explained some weeks ago, I experienced random shutdowns with my new 2010 iMac 27" 2,8 GHZ when I upgraded it to 16 GB of Ram with 4 modules CSX sold by Macnificos.com (Spain).
This shutdowns happened many times when I was surfing the Web. Most of them happened when I visited Marca.com with Firefox, but surely the system could have shutdown while I was carrying out any other task.
There was no shutdowns when I downgraded the iMac to a 4 GB, 8 GB or 12 GB configurations with the same modules. The iMac shutdowns happened only when it was 16 GB.
After installing 4 new CSX modules the last week, my machine continued shutdown randomly.
Finally, I've received 4 new 4GB Samsung modules to replace the CSX RAM this friday, and I haven't experienced more shutdowns since I installed them.
My conlusions are:
1) Only Samsung modules can be used safely to configure the new 2010 iMac 27" with 16 GB of Ram, although modules from other manufacturers can work in certain specific equipment or for some users, but not all.
2) Similar problems on other models of iMac (iMac 24", iMacs from 2009) can don't be related to a Ram problem. The shutdowns happened on this other machines with the same symptoms can be produced by another problem.
3) In many cases, it's possible to use RAM from manufacturers as Kinston, Hynix, CSX, Corsair or OWC in the iMac 27" 2010 but only with configurations with a maximum of 4 GB, 8 GB or 12 GB. With 16 GB configurations, the modules of all this manufacturers can produce or not random shutdowns, althought the modules are provided by Apple when we bought the machine. Apple includes different manufacturer RAM to their iMacs, but probably only those suministrated with Samsung modules can work with 16 GB without shutdowns.
4) Of course, PRAM reset, SMC reset, completly Mac Os reinstall and other similar procedures doesn't solve the problem.
5) Apple don't know how to solve or fix this. Apple support offers changes of power supply, motherboard or complete machine, but no one of these steps solves the problem.
6) Apple isn't informing about this RAM problem, and their users and clients are completely disinformed. Everytime the problem appears on a new machine, its user has to spend a lot of time, perhaps sending its equipment to repair without satisfactory results, until he found the solution explained on this forum.
7) One more time, Apple is not behaving as we would wish. They would have to mention the problem to new buyers or at least to its technical support services so that they do not replace equipment, power supplies and other components without purposes. They would have to propose directly a change of ram memory to Samsung modules while their engineers investigate the problem and find a definitive solution.
8) If you are experiencing this problem, the only solution today is use Samsung RAM or configure the machine with less than 16 GB.
In order to finish, I want to be thankful to Macnificos.com by its amiability and help to fix my problem. They acceded to change my 4 modules of CSX for 4 modules of Samsung and now I can work without problems.
oh Dear, my first imac ever and have the same problem plus the fan of the imac turns on suddenly and makes an awful noise, just 3 days unpacked. i guess better go for a refund or something (i hope so) 😟
I don't believe it has anything to do with the RAM maker.
I've noticed that the switch-off happens when the iMac goes from idle to 100% power. This can not be overheating. The thing is that the i7 is designed for hyperthreatting when more than 8GB are installed. I believe it has something to do with the system switching between various CPU states. Since we usually run multiple applications at the same time what happens is that the computer switches from turbo boost to hyperthreatting. And then it happens. On my iMac it always happens is either of these two scenarios. I go from idle to full power all at once where all 8 cores (4 real ones and 4 simulated ones) work at the same time. Or when I run the flashplayer on Safari with multiple windows open with tons of animated advertisments. I noticed how it has aversion to flash content from European media websites. Some of those European media websites are totally overloaded with advertisments. And it's again having to run all the different animations at the same time and that's when it stops.
In the first case, when I gradually increase the load on the processor so that it first does one task that uses one core and then another and then yet another until I'm running 8 tasks at the same time each using one core, nothing happens. But if I start all at once like after having put all on hold and then started up all at once, it switches off. It can't handle peak performance start ups. The iMac i7 2.93 with 16GB Ram can't handle this scenario. Happened both in Snow Leopard and Lion.
My iMac is a 20" 2008 model. I changed RAM and upgraded harddrive since it was almost full. After it shuts off, when we turn it back on, the fan comes on at a very high speed. l have to unplug it then plug back in to restart without the fan. It's not running hot. Fan works normally at other times.
the iMac mid 2011 27in that i thought was the best thing ever has turned into a nightmare! I am not sure what to do with this, not only do I have the shut off problem- when I leave it for a few minutes or put it to sleep it shuts off completly and then it is very hard to turn it back on, numerous trys before you can finally hear powering up.
I also have the issue of half the screen being dark, it gets darker the longer I use the computer. I did go to the apple store and amazingly some of them had never heard of the problem although there are numerous forums discussing this issue. It wasnt until I was talking to some of the salesmen who mentioned it was his last day. Not only did he agree there was a problem but he also said lots of people have told him about it.
so now what to do with a 2K door stop??
I am out of warrenty, it seems crazy to trust apple again if they have this much wrong with one computer and wont even acknowledge the problem or offer a fix.
