Late 2012 iMac locking on Sleep

Hello McHerb, if it is the correct spec, and corresponds with the data in the Crucial configurator, they will certainly help you (even when not, I think): they have a very good reputation. Normally they take the modules back and send new ones. I have good experiences with Ram and SSD from Crucial.

The spec seems good indeed, as you said, the only thing I am not sure about is the latency CL11, these modules are available with latency 9 and 11.

Do you have the Fusion Drive or the 1TB HDD?

No complaints on crucial sofar. They are very responsive. I'm already a happy customer for some time of their SSD's.

I have the fusion drive 1TB. For the rest it is the standard 3.4GHz, i7, 27", 8GB 🙂

My late 2012 iMac (27", quad core i7) has the original memory supplied by Apple, and has sleep issues...

I've run the built-in diagnostic (option-D on startup) and it's found nothing wrong.

I have no experience with he fusion drive, maybe that system is even more sensitive for the specifications of the Ram (?).

My iMac 27" i7 1TB Fusion 16GB RAM (original Apple) has the same issues.

Cant wake with Mouse or Keyboard and when i press the Powerbutton (< 1s) the Mac start like after turned off ...

Update:

with help from crucial the problem has been pinpointed to one of the 8GB modules. The other module does not make the iMac crash when coming out of sleep. The malfunctioning module has been send back to crucial by RMA.

I'll post an update when I get a new module from crucial.

very good 🙂

When i removed every USB device - connected thru a Logilink 10 Port HUB it still crashes in sleep.

When i removed the Voltage connector from the HUB ... it sleeps well ...

USB without power supply and every HDD, Scanner ... plugged in - it sleeps well ...

It seems that there is a residual current (fault current? Don´t know the right english word) flow "back to my Mac" and kill it while in sleep ...

Or the Logilink with the power is not good! Did you try another powered hub?

This one worked well with the white iMac and the previous Alu iMac ... only the iMac late 2012 is to sensitive ...

The 2012 is USB 3.0 ! Try another hub.

USB3.0 has to be compatible with USB2.0 ... maybe the 3000€ IMac is not as good as every cheap PC?

at the moment i have a Transcend 4Port USB3.0 hub (with power supply) directly connectet to the Mac and the 10port to the Transcend (without power supply) ...

still it works ....

Of course USB 3 is compatible with USB 2, but the speed and power specs are different. It has nothing to do with the make of the computer. Try another powered hub.

update:

I got a new 8GB module from crucial via RMA. The new module seems to behave fine - no more issues on sleep and wake up. If new issues occur I will reply back to this post. Otherwise, it is closed for me. :-)

Try another USB hub!

I am on my third replacement iMac (27" late 2012), the last two are exhibiting identical issue: the machines will go to sleep and will not wake up, and in addition the power button is disabled, i.e. pressing the power button will not restart the machine.

I am guessing that the SMC crashed, as the only course of recovery is to reset the SMC by removing power, pressing the power button for a while, and attempting to restart (does not work all the time, so I sometimes have to repeat the SMC reset procedure).

after doing some research on the net, I found how to see the hibernate mode, and found out that my machine was set to hibernate mode 5, which is NOT an approved setting, see below.

I used the system pref -> energy saver and clicked restore defaults which restored it to 0.

HOWVER, upon plugging in a powered USB hub, the hibernate mode was automagically reset to 5.

once at hibernate mode 5, putting the machine to sleep manually exhibited the same symptoms, i.e. not wake from sleep and disabled power button.

this was done with an apple care tech on the phone, and he recommended replacing the iMac once again, and sending me a fourth replacement!

overnight I played some more with this

I reset the hibernate mode but this time to 3 and I tried a different USB hub.

hibernate mode stayed at 3 after plugging in the USB hub.

I then created a small shell script to monitor and display the hibernate mode:

function showhibernate() {

while true

do echo -n `date` " ";pmset -g|grep hibernatemode;sleep 10

done

}

and executed it overnight

this evening after I came home from work, I noticed that the hibernate mode somehow was switched from 3 to 7!?

unfortunately, I did not have the echo `date` on the first version, so I do not know when it was switched from 3 to 7.

however, the machine did wake up from sleep... (so it seems that 7 is not as bad as 5?)

I am guessing that some powered USB hubs cause unexpected changes to the hibernatemode, which in turn cause the SMC to crash, disabling the power button.

why plugging in some powered USB hubs but not others will cause the hibernatemode to switch to 5?

why hibernate mode would automagically switch from 3 to 7?

neither 5 nor 7 are documented in the man page, and the only recommended modes are 0 3 and 25:

We do not recommend modifying hibernation settings. Any changes you make are not supported. If you choose to do so anyway, we recommend using one of these three settings. For your sake and mine, please don't use anything other 0, 3, or 25.

For now I cancled the shipment of the fourth replacement, as this seems to be an issue affecting all iMacs (and a specific USB powered hub), so that a new machine will not resolve the issue...