OSX Lion + 2011 iMac 27'' + Video = Freeze

Hi all,

I realise this topic is dated but hopefully it'll help someone out there with a 5750 still kicking around.

Found this thread after helpful advice from Andrew Humphreys as I've had artifacting issues with my Mid-2010 27" iMac for quite a while.

The first time the problem occured, the 5750 was replaced under Apple Care. I also had a hard-drive nearly die but luckily caught it in time because Apple run their devices way too hot. After the replacement GPU (and hard-drive), I installed iStat and cranked up the minimum fan speed to keep things cool.

Fast forward a few more years and artifacting is getting worse but, like most of you, mainly during the cooler months which made me think it was drivers and not heat. Unfortunately there was no real way to easily stress the system to prevent lockups (they'd happen frequently and sometimes with minimal artifacting) so I researched on modding the GPU to prevent it downclocking or undervolting.

I had recently swapped out my 2TB WD Black for a 1TB Samsung 850 EVO SSD (after moving to a NAS for media and backups) and was determined to get a few more years out of the Mac so cleaned up the heatsinks and reapplied thermal paste to both the GPU and CPU.

But Winter came and nope, still no good so found the details for flashing the BIOS to either run a higher stock clock speed or overvolt. After loading the stock BIOS, I figured out it must've just been due to the drivers using the wrong profile so set all 4 profiles to 700Mhz on core, 1000Mhz on RAM and 1v on die.

Unfortunately it took a bit of time to do all this as I had to load W10 onto a new partition but rebooted and no more artifacts.

Let's see how long this lasts!

If the videos are Flash based you may need to update Flash, visit Adobe's site for that update.

Having the same problems including imovie freezing! Only started this morning after upgrading to Lion! But no one has come up with a solution YET! Instead of hitting the power button try clicking on the dock logo and force quit. A report comes up that you can forward to Apple. See if that works!

Just found three short movies in iPhoto 8.1.2 are associated with a Quicktime freeze of almost all computer functions since Lion was installed. Activity Monitor has to be used to force quit.

I keep Activity Monitor in the Dock because of other types of freeze experienced with 10.6 and 10.4.

The Dock seems to be accessible when all else has failed.

Good to know I'm not the only one experiencing this problem. Don't know how many times I had to power off my mac today beacuse of this.

Mid-2011 27" i7 12gb ram

Yep. Just bought my iMac 2 weeks ago. This happend to me twice. I should have downloaded that flash last night. I will do it now. Geez. This is rediculous... not a good start to a new OS system. Does this stuff happen at every update?

I can't even click on the Apple to force quit... 😠

Kellie,

Normally updates go smoothly however there are always some users that have problems. Those users don't represent the general population. I have updated from Tiger to Leopard, to Snow Leopard and now Lion on the same machine with no drama. Whenever doing any major system update there are some basic precautions to take. On the next one feel to ask what you should do to prepare and some experienced users will give you some advice.

rkaufmann: Shoot. Too bad I didn't think to check in with advanced users prior to installing... now I know.

I don't want to screw up the computer by having to turn the off switch everytime... I know that can't be good for me to do that every time. Is there a work-around for that? Keyboard shortcut?

Plus, the new feature for Lion to automatically restart if the Mac freezes didn't come through either.

For new MAC users, all this can be quite daunting. I've manage to figure things out... using this forum community mainly...but for users who don't want to or don't know how to research to find answers can be overwelming.

I also took up your prior advice and did the Java update. Thank you for that. I'm just hoping things run smoothly from here on out and that was the only needed fix.

wanted to add: I've noticed there are various updates for iMovie, iPhoto, Remote desktop, Garageband... that were just launded a few days ago...should I just assume that those updates are needed too?

I feel like I'm constantly asking questions, complaining and sound like a broken record... but you know what? I'm a complete newbie.

Gotta start somewhere. 😉

Don't turn your computer off, it will react better if you simply let it sleep when not being used. Please re- read your manual it's got important stuff in there! One tidbit is on page 15 where Apple says:

Putting Your iMac to Sleep

If you‘ll be away from your iMac for less than a few days, put it to sleep. When youriMac is in sleep, its screen is dark. You can quickly wake your iMac and bypass thestartup process.

Also as a new OS X user I'd strongly recommend bookmarking and using:

Switch 101

Mac 101

Find Out How Video tutorials

As for updates, let Software Update manage your updates. If it tells you an update is available download it per the on-screen instructions. You can set Software Update to automatically check daily, weekly or monthly in System Preference - Software Update. I have mine set for daily.

There are also lots of tutorials on Apples site for the iLife apps. You can find those by doing a Google search such as IPhoto Tutorial.

And yes you're right you have to start somewhere.

Thank you for the links.....

I've been to Find Out How about 50 times in the last 2 weeks. That's a great resource too. I created a music video using iMove literally as soon as I took the computer out of the box. 😉 It turned out quite well for my first and being a steep learning curve.. lol!

I want to make sure you're not misunderstanding me:

I NEVER just shut the computer down. I always always put it to sleep.

The reason why I had to do a hard power off is due to the two times it froze... and not able to do a force quit.

I may be new, but I do have common sense.

As far as updates: good to know. I'll set the preferences to do a daily check on updates.

Thanks again. You've been super helpful.

Your welcome and enjoy the new iMac.

Hi,

iMac mid 2011 i7 3.4ghz, 1To,Ati 6970, 12Go DDR3

Sometimes, when i click on a youtube video, the iMac crashing. I need to force a restart.

rubenlx wrote:

Hello.

Got a brand new 27'' iMac, installed Lion. The machine freezes randomly when starting to play videos, either on Youtube, Quicktime, iTunes.

When it freezes, the mouse still works, but the machine doesn't respond to any command, requiring me to hit the power button and restart the computer.

Searched on kernel.log and system.log, and found no crash/error/message.

Anyone suffering from the same problem? The machine is pretty solid, been running some OpenCL kernels too and they are ok. It's only video decoding (possible on the GPU) that seems to freeze randomly.

Exactly the same problems :/

What version of OS X are you running an dwhat troubleshooting have you attempted. Please be specific and detailed.