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My 27"I7, 2T HDD imac has narcolepsy too. Mine goes to sleep and won't wake up unless I unplug it, etc. Took it to the genius bar and they reset the SMC and sent it home. They can't reproduce the problem. I've had the problem off and on sinc eI bought it in Dec 2009. It got better after the firmware update, then became constant, slipping into a coma several times a day after I attached a firewire 2T gdrive to use as my time machine backup drive. What's very odd is that I have to press the on button twice to get my machine to turn on. The first time just the fan goes. I press and hold the on button to turn it off, then press it briefly to start it. It starts right up. While poking around the apple support site, I came across this:
"Only a Mac running Mac OS X v10.6 can Wake on Demand. New Macs ship with Wake on Demand enabled by default, but for some earlier Macs this option must be enabled using the steps below. Macs that have Wake on Demand enabled will occasionally wake for a brief time, without lighting the screen, in order to maintain registrations with the Bonjour Sleep Proxy. On some Macs, sounds from the optical drive, hard drive, or fans may be heard during these brief maintenance wakes."
I'm not on a network and I don't have a time capsule, nor do I have any idea what a bonjour sleep proxy is. But it does seem that my computer is stuck in a "maintenance wake" when I first try to restart it and sometimes when I think its asleep, the fan is on, so could this be a part of the puzzle?
For now, I just set the computer sleep time to "never" and it is working for now. I've also set my personal sleep time to "never another apple product."
On April 14th, Apple released a new firmware for 27'': 27-inch iMac EFI FW Update 1.0. It was supposed to "resolve an issue that prevented the display backlight from turning on after powering on the iMac."
I thought my problem (the same one as everybody here) was finally being solved, but no luck at all ! After applying this new firmware my iMac still doesn't wake up after a sleep 4 times out of 5 !!!
And when I read that the Apple assistance is useless, what can we do ? I have a USB keyboard, and no USB hub, no external HD connected, nothing, just the plain vanilla iMac 27'' bought in December with standards software... Will a reinstallation of Snow Leopard solve this ??
This started happening to me the day before yesterday when I moved back into my mom's house. It seems to happen sporadically but I may have noticed a trend. My mom keeps her house warm. Like 76 degrees Fahrenheit warm. My boyfriend's house is generally kept at about 64-66 degrees Fahrenheit, 68 at the warmest. I never had any problems there.
If I start the computer up in the morning and immediately put it to sleep using the "Sleep" command from the Apple menu, I can then wake the computer up a couple seconds later with no problem.
However, if I'm using the computer for a couple hours, long enough for it to heat up and THEN put it to sleep and try to wake it up, it refuses to bring the screen back on. The hard drives will spin back up, but I got a blank screen.
I'm thinking my problem may be the temperature of the room, so I have a fan blowing at the back of the computer constantly to keep it cooler. If I don't have the fan on, the top of the iMac gets red hot to the point where I almost burn my hand. I'm not using graphic intensive programs, just browsing the web, chatting with AIM, etc. However, even with the fan, after a couple hours of use, the computer refuses to kick the screen back on upon waking up from sleep.
I guess the only thing I can do is deal with it a while longer and see if the problem persists when we move into our new house.
I have had this same problem and it has driving me crazy for months. I have an Aluminum / Black / glass 20" imac. It is the first release of this new design.
Several months ago this "Not waking from sleep" started.
I have read and read, and tried everything I could find and nothing worked. Including VNC and ARD attempts.
I made a discovery about ONE months ago and have waited this long to be sure it solved my problem and so far it has.
Unfortunately it is a PITA, but I only plug in a Firewire 400 or Firewire 800 device when needed. YES! what I am saying, is do not put your computer to sleep with any firewire devices plugged into it.
I have found this solved my problem, and hopefully will solve other peoples problems, although I am sure not everyone's.
If I don't have the fan on, the top of the iMac gets red hot to the point where I almost burn my hand.
FWIW, the top of all aluminum body iMacs feel unusually hot in comparison to the plastic body ones, but a large part of that is because aluminum is a very good conductor of heat & plastic is a poor one. Apple takes advantage of that fact to conduct away some of the heat from the internal parts to the aluminum case that in the plastic body models would have to be carried away by the air the fans blow through the case. This results in quieter operation because the fans can run slower. Since what matters is not the temperature of the case but of the heat-sensitive internal parts, this often leads users to think the aluminum body iMacs run much hotter than the plastic body ones when it isn't true.
If you are skeptical about this, try this experiment:
Heat up a coffee cup full of water to a little below the boiling point. Set a plastic spoon & a metal one into the cup & let them both heat up to the water temperature. If you touch the handle of each one briefly, the metal one will feel like it is about to burn you but the plastic one won't, even though they are actually at the same temperature. That's because metal is a better conductor of heat than plastic so it transmits heat to your skin faster & raises your skin temperature more quickly.
The same thing happens when you touch the cases of the iMacs. The aluminum ones feel hotter even when they are at the same temperature as the plastic ones. What matters is how hot the insides get, but you can't judge that by how hot the outside gets. For that, you need some tool like iStat Pro that reads the temperature of various internal systems.
An iMac bought a couple of months ago, worked as expected for a while, then began to resist being woken up. I've noticed in my case that if there is some fan/disk noise when I come to wake it up, it's likely it'll refuse. If it's totally silent, it may respond. The only way to wake it is to reach round to the power button, power off and power on (and pray I saved before sleeping).
This is on 10.6.3, no firewire, a printer and external drive connected by USB, and wireless mouse/kb.
Just talked this one through with Apple Care, who recommended starting with the old zap P-RAM manouver - power down, disconnect all cables, hold power button in for 10 seconds, reconnect cables, power on and immediately hold down 4 keys: Cmd-Alt-P-R (an easy chord for piano players if your thumb covers both the control keys). Oh, and if you have a bluetooth k/b, you may just need to dig something older out of the attic - mine didn't connect in time to make the Zap command.
Since mine's an intermittent fault, only appearing to happen when there's machine (fan?) noise during sleep, it isn't possible to force it to go into 'sulk' mode to test whether this is any kind of fix. But apparently it's a first step we have to take to rule out quite a few alternatives. Progress report here, as and when the intermittent situation crops up.
Meantime, may I ask - is everyone who experiences this problem hearing noise from the machine when it's in sulk mode? If you can tell the difference between fan and disc, is it always fan noise that indicates you'll have trouble waking it?
Mine just did the same thing the hard drive is about to blow. 50ºC is way too hot for a mechanical device, they'll last 9-12 months tops. For some reason cooling doesn't operate properly in sleep mode or something especially if you are running a virtual machine (Windoze) or have EyeTV or some other background processes going on.
Try vacuuming/blowing out through the air inlet, but if the drive has already had a few hiccups it's certainly heading for the grave sooner than later.
I'm still having the same issue of it not waking up.
I have changed it to the computer never goes to sleep. I don't want to have to change it to display never turns off.
the only thing that will get it to wake up now without powering down and back up... is to turn off the second monitor I have connected through the display port. as soon as I turn off the monitor, the main screen pops on. and then I turn the second monitor back on and it's just fine.
I have 2 firewire drives attached to it, and a 24" monitor through the display port. I never had a single problem with it until this past firmware update. it started directly after the update. it's getting beyond frustrating.
I believe I pinpointed my catalyst.
If my iMac goes to sleep with my second monitor (connected through the mini display port) powered on, it will not wake back up, without help. If it's not been too long, I can simply turn off and then back on the power on my second monitor to jog it awake. if it's been several hours, even that won't work and my only answer is to power down and the restart.
If I power off my second monitor and then it goes to sleep, it wakes back up at the drop of a feather as it is supposed to, as it had done so until this past firmware update.
it might be of note also that the monitor I am using is not a apple cinema display, rather it is connected through a mini display port to DVI-D connector.