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

I have this video card. NVIDIA GeForce GTX 680MX 2048 MB.

My model (A1419, EMC2546) i7 3.4GHz has nVidia GTX 675MX GPU, not AMD.

Guys, Fametown and Cre8tive, - How can we get Apple Inc. to recognise our random iMac shutdowns?

My specific model is the late 2012 i7 27" (13,2) with NVIDIA GeForce GTX 675MX.

It could be a faulty Power supply part problem or Logic board or other?

At any rate it will cost us $ and the inconvenience to repair.

Yes, let's do some research on more direct contact.

Thread about similar symptom on iMac Late 2012 :

https://discussions.apple.com/thread/6176570

https://discussions.apple.com/thread/6432787

https://discussions.apple.com/thread/2473276?start=0&tstart=0

This is my video recording. As you can see, it is sudden black out and need SMC reset to power on.

This also happens on even recovery partition boot, during OS installation process.

https://onedrive.live.com/redir?resid=8DAC765079965977!61357&authkey=!AI0eyx0TWA HHZcA&ithint=video%2cmov

It looks like it is not OS or software issue, this happened in Mavericks and other clean install OS too.

What I've done so far :

- Replaced power supply (by Apple)
- Replaced with new RAMs

- Replaced Logic board
- Replaced HDD
- This is not heat related problem. Temperature is ok. Symptom shows on even cold booting process.
- Sometimes it runs ok for one or two days.

Now remaining parts are CPU, LCD and cables. I believe CPU fault or bad LCD is the least suspicious thing.
I am trying to replace power supply connector cable (connects power and logic board).
Also I will try replacing display signal cable.

It happens to me too.

In my case I need to unplug the power cord after the unexpected shut down and wait 15 minutes.

Yes, same here. 15mins sometimes half an hour unplugged before the iMac restarts.

What model iMac do you have?

iMac 27" late 2012.

Just a heads up, Seems that the TechTool Pro app can offer some pertinent info on our macs. I have not tried it yet. 99USD.

Here's an email reply just received, where I asked about various possible tests.

'Hello,

Thanks for your email. The new sensors test in TechTool Pro 8 includes tests of a variety of your Mac’s internal sensors, including those related to your power supply. If the electrical output coming across the sensor for your power supply is outside of the acceptable range for that particular sensor, it will trigger a failure in that test.

Thanks,

Micromat Help'

I just used TechTools 8 and all the tests are OK. Yesterday my iMac shutdown more than 10 times during the day. Brrrrr.

I just made this video. I use iStats Menus 5 for the sensors.

https://www.youtube.com/watch?v=fal-OzSzF6Y&vq=hd1080

All it's ok just before the shutdown ???

It's been a year now... I have the same model as most of the people here... Apple please help to fix this issue!!!

This machine is the single most expensive item I've bought straight out of my pocket and it only lasts for 2 years?! This issue is obviously Apple's fault and why are we paying to fix something that you guys caused?

I hear you 😉 .. It is time for Apple Inc. to own up and rectify the random shutdowns affecting so many - iMac Late 2012 27".

sfgswedfstfsd, I have found that shutting down the imac at night (before bed) and removing the power cord from socket, sometimes allows a full days usage without shutdowns. When inserting the power cord to restart, make sure the power is switched off, insert into imac, switch on, then wait 5 seconds before pressing the computers rear power on button. Run disk repair permissions utility often as well - not sure if this helps, but no harm in doing so.

Also, if upgrading to 10.10.3 use the Combo updater.

GOOD LUCK

Yes! I've also found that the longer you leave the iMac unplugged, the longer the iMac will stand before the random shutdown. However, the iMac would need to be left alone plugged for a couple of days. I've tried this before and it'll stand for a week or so with no problem.

I swear this $3,000+ machine is designed for anger management... Been using my Macbook Air for almost a year because I'm so tired of it. This couldn't be called a computer if it doesn't even freaking work properly!!! Sigh.. sorry for all the anger.. Been keeping it for a while now.

Our iMac 27 (late 2012) is doing exactly the same thing. Random crashes requiring SMC reset. Resting NVRAM crashes the computer every time.

Taking it in to Apple for repair soon. Fingers crossed they will fix it or replace it.

Please post the results from Apple repair. There are a fair few here with the same computer and similar problems.

I cannot let mine go, as I need it for work daily. Either a free repair or a new computer would be the proper result I reckon. Good Luck!