my imac won't wake up from sleep mode with mountain lion

SOLVED...Atl least for me. I upgraded to 16GB non Apple memory 5 days after I got my iMac in Sept '11. Don't know why all of a sudden it failed out in Sept '12, but that was the issue...bad memory. Also it was non apple.

Applecare came to house and they swapped power supply, then hard drive, both originals were fine so the orignal hard drive went back in and the replacement power supply stayed in. A logic board was ordered as then next step.

Next day Applecare came out with a new logic board., Same thing, power on, but no lights or much activity. Apple care guy said it was strange that there wenen't even any beeps on startup to give an error clue.

So, he called Apple and they brainstormed for a few more minutes. He then noticed that there was 16GB instead of 4GB. I gave him the original 4GB and the computer started back up without any, repeat...ANY problems. I'm happy now. Has anyone else changed memory? if so, the guy said that it's best to use the apple memory (closed loop type of thing).

Jeff

Hi All,

Very pleased to find this thread. I have a three week old iMac i7 with 16GB RAM and a Radeon 6970M.

Just a bit of background, I am a video editor currently doing a lot of video compression and encoding through Apple Compressor (from FCP Studio 3). The length of the jobs is long - the last batch was looking at a 20hr completion time.

I left the machine running over night, as I have been over the last week or so, came to check it this morning and to my horror the thing wouldn't wake up. I thought it had just hung and shut itself down until I heard the fans running, googled it and came accross this thread.

My USB mouse, wireless keyboard nor the power switch would make the display come back on.

Unlike one of the users above my iphone wouldn't display a charge when plugged in.

I think this is a problem with the System Settings incorrectly regulating the machine.

The worrying thing is, system sleep and display sleep were both DEACTIVATED. This is becuse I am running Avid Media Composer and system sleep can interfer with it's processes.

Screen Saver, however, was turned on for 15 mins of inactivity.

Since I got the machine I have had periods when Screen Saver and Display Sleep have been turned on to activate after 15mins. I had noticed that often I could come back to the machine after more than an hour and neither of these settings had activated.

From the sounds of it Apple need to get this sorted out.

For my part I have lost more than 12 hours of work - not happy.

Time to call Apple support me-thinks.

I have finally solved my problem. I have upgraded the memory for my Early 2009 24" iMac from 4GB to 8GB over a year ago and never have sleep/wake up problem with Lion. Since Mountain Lion, the machine refused to wake up. I have followed the suggestions in this thread:

1. Downgrade the memory back to the original 4GB ---> DOES NOT WORK
2. Uninstalled iStat Menu and Fan Control ---> DOES NOT WORK
3. RESET SMC (Shutdown the iMac, Unplug the Power Cord for 1 minute, Plug the Power Cord back and Start the iMac) ---> WORKS

Well I hate to say I figured out (solved...sort of) my problem. Required a trip to the Genius Bar. They ran their internal diagnostics on the computer and the heat sensor was throwing an error. After a while, we found the GPU was running hot, likely causing the heat sensor issue.

So as my machine would run for a while, it would heat up and then the screen would shut down.

After thinking about it a little, I do recall issues about a month ago where iTunes was having issues with rendering some movies (causing skipping in the video but not the audio).

So off she goes to the repair hospital....

Sorry folks, hopefully my solution isn't a help to any of you.

I also had the same waking from sleep problem since I bought my iMAc 2+ years ago. Took it in to the Apple Store a year ago with no positive results. Took it back this summer and the technician and I noticed that on the Activity Monitor that the Spotlight was always at 95-98% usage. It was always searching for something. The technician turned it off, we waited and turned it back on. By the time I got back home, the Spotlight was rebooted and I haven't had a problem with waking from sleep.

Hi All

After trying many of these suggestions the one that worked for me was

clicking and moving the mouse around - it takes 5-10 seconds to finally wake

The iMac was completely silent, no fan etc. so I really thought it was hardware, especially because the power button seems disabled too.

In Bluetooth settings I also made the wireless keyboard and mouse my favorite in the cog settings (not sure if that helped).

-Also reinstalled combo update to 8.2 which didn't work

-Unplugged for 10 min. - didn't work,

-tried usb keyboard and mouse - that worked but I think it was shaking the mouse around that did it so I tried the wireless and seems ok. Not obvious at all!

Apple why the slow response time waking? It's the newest hardware with M.Lion and not a software upgrade from Lion

Maybe this thread will help:

https://discussions.apple.com/thread/4144587?answerId=19065360022#19065360022

The way to fix this is going to system preference, bluetooth, advance, clicking on "allow bluetooth to wake machine". No problems after that..

my first iMac (27" late 2012) exhibited problem with the fan going on full blast upon connecting to power, quiet when the machine was booted, and on full blast again when the machine was off. called apple, and got a replacement.

I am now on my third replacement iMac, the last two are exhibiting identical issue with sleep: 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 view the hibernate mode, and saw 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 the hibernatemode 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 new iMacs (and a specific USB powered hub), so that a new machine will not resolve the issue...

I started having this problem on my 27-in iMac and googled to find it this discussion here. Unfortunately, none of the suggestions worked, but I did find a solution at least for my problem that may help others. If you have DriveGenius TechTool Pro installed, one or both of the monitoring apps may be causing your problem. I disabled both monitoring portions, but kept the apps installed to allow manual testing, and my won't wakeup problem was resolved.

My issue with my mid 2011 imac going to sleep and not waking was pre-memory upgrade. In other words it started with the original 4 gb ram, then I upgraded to 16mb ram and still have the same problem. I can not understand why Apple has not addressed this problem. signed, READY TO REVERT BACK TO WINDOWS.

Send Apple feedback. They won't answer, but at least will know there is a problem. If enough people send feedback, it may get the problem solved sooner.

Feedback

Sleep – Slow Wakeup/Requires Reset

Sleep - Wakeup