27 iMac (2012) crashes and requires smc reset to turn on

Here we go again!

I had the power supply replaced three months ago and it's still happening. Third apple support call coming up. This is not over!

This will be my second time returning my '27 iMac (2012) to the Apple Store. They first diagnosed the issue saying it was a PSU so they went ahead and replaced. A month later, the issue is recurring.

I only have 20 days left on my warranty, now I'm worried.

I've been getting good results with this technique over the last three months. In December when the shutdowns were happening very frequently and I was using my computer a lot more intensely due to winter break, I started unplugging my computer every night. I've been getting more lazy of late about unplugging the computer and I've even left my computer on for three days. That seemed to trigger a relapse yesterday when it shut down in the middle of a game. It seems to like being powered off as much as possible.

Hi all,

have the exact same symptoms on a late2012 27" iMac with core i7 and the 680MX graphics card which I bought to be safe for some years of innovation. I've not done any reparing other than checking if different RAM configurations are the issue yet and am very sceptical of trying anything after reading through this. Has anything other than being lucky and getting a new Mac worked? It seems to not have, but I just wanted to ask... 😟

Same exact problem here.

Late 2012 27" iMac with NVIDIA GeForce GTX 680MX 2048 MB

Purchased around April, 2013. Random shutdowns started last summer, so a little longer than two years after purchase. I've had it in to the Apple Store just once so far, a week ago. They tried to replicate the issue by letting various animations run in the grapher program for about 36 hours, but no dice.

Their diagnosis was that it was fine and that I should take it home and unplug all my peripherals in an attempt to isolate the issue. Yeah, so did that, and two days later, boom, shutdowns. The first one came after only working on it for less than hour. Happened when I went to open a photoshop doc. Next night, I had two shutdowns within 15 minutes of each other. This time, I only had Chrome and text edit running. Then a third one later that evening.

Going to schedule another appointment soon because this basically renders the machine useless to me. Unfortunately after reading through this thread though, I have a feeling I'll just be out of luck.

I see it a lot brighter now, so I'd like to give some hope to you, too. Firstly, with the amount of cases, the words "planned obsolescence" need to be dropped here. I cannot believe the immense efforts apple seems to go to not acknowledge that this series of iMacs has serious issues. Also, not at all replying to this gigantic thread made me get to the decision to leave apple products forever after using them exclusively for my whole life even before they were "cool". If some manager reads this, this is your doing and I will keep telling everyone I know, that Apple sells faulty (expensive!!!) products and does not stand by it but chooses to ignore their customers.

Sooo, now the advices:

I talked to someone on reddit with the same problem and he did some research: People that replaced the power supply are mostly happy now. The problem seems to be, that even the licensed workshop I'm going to because I lack any AppleCare does not simply want to replace it. They want to diagnose the problem and then make me an offer. 😟 Soooo, if you get your people to replace the power supple, then there is a chance you're fine, but getting them to do that might prove difficult. I'm very close to getting the parts and tools and opening that thing myself since, as you said, it's basically useless now.

As a short-time solution and kind of troubleshooting: Try disconnecting your iMac from power completely everytime it is shut down (especially during the night) and you should experience much longer uptime. If not, there might be something wrong with the mac outside of the power supply. So far it worked quite alright for me.

So about a week later after the Logic Board (and over a month the power supply was replaced as well) has been replaced, it shut down abruptly last night again, very frustrating.

I'm experiencing the same type of problem, but on a model ( imac 27' ) of late 2013

Despite the different release date symptoms are the same as those multiply exposed here.

It said in that thread that Apple takes the problem seriously, right ?

I found it hard to find information on the problem and to find confirmation that it is not an isolated problem

Hey guys. Count me in.

Same problem.

My iMac: 27" iMac late 2012 i7 3tb Fusion Drive Geforce 680mx

Started 5 weeks ago. First I thought it might be my hard disk. So I took my Mac to an Apple service provider. They changed my hard drive for free because there is a replacement program. So after I got it back everything was fine. But a week ago the same problem occurred again. Sudden shutdowns with no warning regardless of what I am doing. It happens when I play games or watch youtube or just do nothing.

So I took my Mac back to Apple Service. Of course they can't reproduce the problem I have described and they tested my hardware. Everything is fine.

After looking for a solution by myself, I came across this thread.

So there is really no 100% safe solution?

What a disappointment. And Apple seems to keep ignoring this serious problem.

Same issue here, started 2 months ago and I tried to wipe the HDD and start all over again. And am using a new powercord.

I guess the power supply is probably at fault, and I can only hope that Apple will acknowledge that there is a problem here.

iMac 27", late 2012, i5 3.2 GHz, 1TB Fusion drive, GeForce 680MX 2GB, bought in Denmark.

Hey guys, i have the same problem with my iMac ! It is a BTO with nvidia 680MX 2GB and i7 3.4. I took it to service but they couldn't replicate the random shutdown. I guess the problem is from the GPU or something related. My iMac doesn't shutdown surfing the web or in sleep, but in Adobe Lightroom or any more demanding GPU app the computer shutdown and than, when i turn it on again the problem happens more often. I can't do anything more than surfing the web check email or something light like that. I really don't know what to do, and i don't want to pay 1000€ for a new logic board, and it seems that doesn't solve the problem. Im in Portugal so we don't have apple stores here, just oficial resellers and some certified apple technicians.

Hey,

So, how is it going? So far so good for your iMac?

So my Mac is ready for pickup. Once again, they replaced the power supply and also the power supply cable?

We'll see how it goes.

To all the new cases: I've been error-free for 2 weeks now with disconnecting the iMac from power completely ⚠ everytime it's shut down. My sample size is daily use of about 4-6 hours in one piece or 2-3 hours twice with 1-2 hours of disconnecting in between. This is also the explanation why the tech support can never replicate the problem: It won't occur unless the iMac is connected to a power supply for more than a certain amount of time. To me this is the definite proof, that there is a power supply problem, but who knows... Perhaps this is just stalling, but let's face it: If I get another 2 years of usage out of my computer, it'll be the "normal" lifespan and after that, I'll buy a real computer without an Apple on it because I don't want to deal with this BS any more.

19 pages and still rolling.

I've had my iMac back from the Apple store now for a couple of weeks. It's had a second power supply replacement after the problem continued with the first one. My engineer was pretty convinced it was the power supply - my advice would be to definitely not shell out for a logic board replacement even if the Apple store recommends it. I'll update the thread if and probably when it happens again.