27" Core i7 iMac blacks out then restarts itself for no reason...

Ravenwood61 wrote:
I just had this happen as well. William, did the PRAM reset work for you?

Yes it did work for me. Sorry took so long to respond.

I bought RAM from Patriot (2 x 2) and my machine was doing the same thing you described.

Also I'd have random program crashes. I took the 3rd party ram out, and all my issues stopped.

No more resets, program crashes, etc.

The RAM is the same exact "specs" as the oem apple ram. That's odd. I wonder if there is something going on with 3rd party ram in the new quad core machines....

Is it a problem with a 4x2GB configuration? A problem with 8GB total?

I have 8 GB in the i7 but came pre-installed from Apple on this occasion. I have read that getting the RAM to seat properly is not easy but it is clearly possible to have a defective module. My i7 is fine.

Just a final update for me. I'm currently running with 4GB of memory and have not had an uncommanded restart since the last update. I'm certain that it was memory related. At some point, I will get more memory for the iMac and I may even pay for the Apple premium modules.

I have had my iMac i7 for less than a month. I am having the same issue... The computer blanks and restarts with no warning whatsoever.

This is happening while editing/playing back video in Final Cut Pro 6.0.6. It is a multicam edit – 5 streams of 1280x1080 HD footage. I know this is very taxing on the machine, however, I am monitoring the system stats and it doesn't appear to be redlining.

Regardless... If it were too taxing on the machine, I could see FCP crashing, but the restart thing is weird. I'm ready to send this thing back to Apple.

All RAM is factory-installed Apple RAM. No modification have been made. All system and app updates are current.

If anyone has any suggestions, please let me know!!

Thanks,

Matt

Yep, I'm also suffering from these instant restarts. In my case it's either overnight or after a afternoon deep sleep when I hit the spacebar to wake the iMac. Zapped PRAM, reset powermanagement to no avail. Just unplugged the usb hub and now I'll wait to see if this makes any difference.

What memory configuration do you have?

I turned off 'restart automatically after power failure' in the energy saver controlpanel and the problem has disappeared. USB hub is connected again. Though it has only been a few days the auto-restart has been turned off I suspect it's the problem on my 27 inch because one time the thing rebooted by itself the second I switched off another gadget in the same power-chain.

Guys,
I heard from my Uni tutor who is called " Mr.Answer", because he is really great educated and experienced sound engineer, that some problems with the memory upgrade can be caused by electrostatic problems. He meant, that if you will mount this RAM touching it with no isolation and not carefully enough, you can damage it not knowing about it. I hope it can help.

A friend of mine has a 27" i7 iMac with the same random reboots, but his trouble extends to a complete inability to boot off a CD or any external hard drive. We've done PRAM, SMC, memtest, etc etc. Still freaks out. I told him to reseat the RAM and if it still happens, take it back to the Apple Store and ask for a new one (but he can't until the 27" i7 models are actually shipping again). Bah.

Same problem with my iMac bought late december in Bangkok.
The restart problem occurs after the RAM upgrade to 8GB.
I bought the ram at the Apple store in Bangkok, the brand is Questek.

I guess the problem is independent of the brand.
The problem happens 2/3 times a day, difficult to say, but I have the feeling it's when I'm scrolling rapidly some photos in lightroom. I haven't reset the RAM yet, wait for calling apple tomorrow.

I swapped ram from Crucial to OWC - things were fine for a month but then started up again. Interestingly enough it happened during scrolling in lightroom then stopped and spread to all web browsers after I reseated the ram.

Mine is currently been at the apple store 10 days now and counting. I called apple directly. They told me they replaced the lcd (yellowing) and HD fan. My gut feeling is that an HD fan will not solve the issue but I am trying to be optimistic. They make is so **** hard to just talk to a tech. I am just afraid I will freak out if after being without my machine for 2 weeks they do not fix the issue.

Got my machine back today after 10 days. Didnt fix anything as I feared was able to get it to reboot minutes after getting it home. Also though they claimed to have replaced the LCD it looks exactly the same - as yellow as before. Really really disappointed with Apple support. I will be making a call directly to apple tomorrow.

I did a RAM reset as suggested above and also I plug it directly to the wall. I was using a UPS and have some doubts about it.
It was working fine until the 28th of february, not one reboot until tonight.

I thought the problem was gone but the reboot happens after scrolling rapidly images in iphoto and having itunes and others softwares open.

Apple's Thailand support is useless, they provide me with a number to call in Singapore...

Not sure what I can do.

I am joining this thread as another annoyed customer. As far as the random restarts on my 27" iMac i5, I think it may be a RAM issue to start. I bought an additional 4 gigs of ram (2x2 Mushkin) when I first bought the computer and have noticed others with our problem having done the same thing. This being said, the restarting doesn't seem to be a heating, fan, electricity issue as I tried out all of the suggestions listed on these forums (including resetting of PRAM).

Lastly, I have noticed the reset happening an awful lot when I'm in Facebook. Maybe it's an unintentional scripting back door something something.

Frustrated considering this was an expensive machine.

This all said, I don't have any yellow screen (or any other) issues and think the machine is great... save for the resets!