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Level 1

5 points

Late 2015 iMac 5K Freezing

Hello,

I recently bought a new iMac 5K and am running into a freezing issue. Any help troubleshooting would be greatly appreciated. Here's the info I have:

Late 2015 iMac 5K 27"
4 GHz Intel Core i7
24 GB RAM (4 GB x 2 factory, 8 GB x 2 OWC)
AMD Radeon R9 M395X 4 GB
512 GB SSD
El Capitan 10.11.3

What happens is I'll be using the iMac under normal conditions (browsing web, writing documents, etc. — nothing intensive like gaming) and the screen will freeze completely. Open windows can't be moved, the dock items don't open or animate, even the clock's time freezes. The only thing that still works is I can move the mouse around the screen but can't click on anything, nor can I switch spaces. My only option at that point is to do a hard shutdown by holding the power button.

This happens about once every 2 weeks.

After restarting, I immediately check the Console's error logs and see two that stand out:

Kernel_TODAYS_DATE_COMPUTER_NAME.gpuRestart

WindowServer_TODAYS_DATE_COMPUTER_NAME.underspace_watchdog_timeout.spin

("TODAYS_DATE_COMPUTER_NAME" is placeholder for what actually appears there)

I'm not educated in reading these type of error logs but in looking at the Kernel file, some of the key info appears to be:

Event: GPU Reset
Hung Channels: GFX
Pending Command from: UnknownCtx
GPU Debug Info (which is unreadable)

And in the WindowServer file, some highlights are:

Command: WindowServer
Parent: launchd [1]
Event: service progress watchdog
Fan speed: 1202 rpm
Then in the Timeline format stacks, I see a lot of reference to the CoreGraphics, CGXServer, and WindowServer

Additionally, I noticed that sometimes when I hard restart from these crashes, iTunes shows a "glitchy" black bar over the scrollbar that jumps and shifts as I cycle through music albums. This appears to eventually go away but definitely looks like something wonky going on with the graphics.

I did also run the Apple Hardware Diagnostic test and no issues were reported.

Based on the above info, is anything standing out as the obvious culprit? And yes, I do have AppleCare, but this is my work computer and to bring it in for repair is quite an extensive process. Ideally, I'd like to first troubleshoot the problem before making decisions about returning or having it looked at by Apple. Thank you for your time!

iMac (Retina 5K, 27-inch, Late 2015), OS X El Capitan (10.11.3)

Posted on Mar 15, 2016 9:55 AM

Best reply

SeaPapp

Level 7

26,486 points

Posted on Mar 19, 2016 9:08 AM

Since you're using this computer for your work you must have a backup computer right? If not that's a poor business decision. Don't mean to sound unsympathetic but that's the way it is. You've already been told that, based on the small portions of the reports you posted, you have a hardware problem, likely a GPU issue and that you need to take it in for service. While it's there you'll have to use your backup computer. Wise choice purchasing AppleCare.

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32 replies

thomasjr

Level 1

4 points

Oct 23, 2016 5:02 PM in response to Rick Morton1

Rick,

Thanks for your input. I *guess* it's nice to know someone other than myself is having problems. I'm sure it doesn;t make either of us feel any better about it, though.

On my end, I've had this trouble since the last OS release, El Capitan. At that time, I couldn't restart normally when it crashed, had to hold the Power button to force a shutdown.

When I first installed Sierra, everything seemed like it was working as normal. After a few weeks, the crashing began again (random restarts browsing, or listening to radio stations online, Photoshop, After Effects, Keynote, etc.); and I'm even having issues with double-clicking on anything (but it could be my Logitech MX Master Mouse software).

I am increasingly suspicious of the GPU in our iMacs. Seems to show up in every error log I send off to Apple after a freeze/crash/restart. I have read a number of reports similar to ours, but with the late-2015 5K iMacs.

I'm certain Steve Jobs (God rest him), would never have allowed Apple to keep adding features while at the same time, eliminating others or not fixing existing problems.

Sorry for the rant, but I'm with you. This might be my last Mac.

Oct 24, 2016 7:29 AM in response to thomasjr

Not encouraging! But nice to hear that someone else has the same problem. Although that always seems to be the case, doesn't it? There are LOTS of people with the same issues and they don't seem to be addressed. I, for one, would never abandon my Macs, no matter what, but I AM frustrated by these problems with a like-new machine running nothing out of the ordinary. Something's wrong. I'm going to call again. Thanks.

Oct 24, 2016 7:56 AM in response to thomasjr

Just an update: shortly after writing in here, I called in Apple. They assured me it was probably not a hardware problem - something I suspected - and likely due to an installation error or/and out of date software. They told me to do a list of things (like resetting SMC, PRAM, caches, etc) that I had done before. But they also gave me the advice to reinstall Sierra - not a clean install, but just launch the setup again. I did that and it seemed to mostly help. I didn't have a crash after that for a week and the system seemed more stable.

Then the system crashed again. But this time I was able to identify the culprit: It seemed to be an out-of-date game I sometimes play... and it was interacting with the Mail app (out of all things?) causing the kernel to panic. As soon as I deleted the game in question, my computer returned to its old stability. No crashes for 3 weeks now.

My point is: the likely culprit is an old app you might be using. A program that hasn't been updated causing it to weirdly interact with the OS causing the kernel panic. Of course it can also be a hardware problem... but kernel panics ARE usually due to software.

Oct 24, 2016 9:21 AM in response to born2bwild04

Was on the phone with Apple senior tech this morning going through all the possibilities, again. Problem was that he kept getting disconnected, phone-wise, and I would have to wait to get the call back. On the third time, he didn't call back but probably will later. Point is, I have no games or old apps. Late 2015 iMac 5K. Pretty clean. No extensions, etc. Have re-installed the OS. Still locking up. Happens in Safari, also Chrome, sometimes mail. When it locks, it's locked, period. Then sometimes it's not responding correctly. For instance, with Safari open and Mail open, sometimes I can't get the window to switch when clicking back and forth. I can move things, select things, but it doesn't let me click on the other window to activate. Then it will. Really strange.

Frustrating

Oct 24, 2016 1:57 PM in response to Rick Morton1

Had the same problems as Rick finally gave up. Went to apple service centre , they reset the machine (and said nothing was wrong with it). I didn't restore any files from back up and reinstalled from scratch all software I was using. Moved personal files and documents manually via an external drive. 1 week later, exact same problem as Rick's. Felt like throwing the machine against the wall. (You would think given Apple Inc has more than $200 bio in cash they would improve customer satisfaction by at least hire a couple of people in Calcutta to reply to these posts!!)

Final Solution : Resett and formatted the drive, bagged the machine in its original wrappings/boxes and sold it at a loss of $300 . Not cool. But it's someone else's problem now. Bought the i27 late 2015 with 32GB RAMS (used)... working beautifully so far (hope I don't jinx it)

Oct 24, 2016 2:56 PM in response to imac21user

Guess what? A NEW UPDATE today!

"adds stability to Safari"

Nice.

Wonder what else it's "stabilizing"?

thomasjr

Level 1

4 points

Oct 24, 2016 4:36 PM in response to born2bwild04

Thanks for your input, I appreciate it. I guess it didn't click kernel panics = software issue. I'll look into any old apps (have a number of them), but rarely run them anymore.

Since updating today to 10.12.1, everything is working well.

And @RickMorton1: yeah, Safari stabilizing....

Oct 25, 2016 1:43 PM in response to thomasjr

I have had the same problem with random freezes, always when using Safari. iMac late 2009. Started after updating to Sierra, never happened before. I can move the cursor, music continues playing in background, but otherwise the iMac is totally unresponsive. The clock stops. The only thing to do, is a hard shutdown.

Several other threads on the same topic.

A clean install of Sierra made the iMac perform much better, but this freeze issue when using Safari occurred again. Updating to 10.12.1 has not solved the issue. I see some top rated users are sure this is a hardware issue. I hope not. For me it started immediately after updating to MacOS 10.12 Sierra.

Oct 25, 2016 3:10 PM in response to viking bear

i updated yesterday and have had no problem, but only on that computer for a couple of hours so we'll see as the next few days go by.

Oct 26, 2016 6:53 PM in response to Rick Morton1

Keep us updated rick i have had the same issues since Sierra been fine since updating but thats been 2 days.

Oct 27, 2016 7:00 AM in response to Whiteman007

Talked to them yesterday afternoon and he had sent my reports to engineering. Their question was if I had tried safe boot or new user. I haven't. So I'm doing that today. Yesterday, the computer was locked when I woke it from sleep. And another lock-up. This, after the update. So we'll see what happens this morning.

thomasjr

Level 1

4 points

Oct 27, 2016 3:41 PM in response to Rick Morton1

Hope you get something out of that. It happens to me randomly (today while listening to Tune-in in a browser), and I need to do work on it, so doing safe boot or new user simply isn't practical on my end.

Thanks for keeping us informed. I want this problem solved, and the random freezing/restarts have been happening to me since El Capitan. Happening less with Sierra, but still unacceptable.

I'm in a HA support group (XTension), and apparently the 5k iMac is not the only machine experiencing issues. In particular, the developer had it happen on his late-2013 MacBook Pro.

Remember when OSX first came out? Seemed bulletproof.

Oct 28, 2016 5:04 AM in response to imac21user

The same problem for me : my machine worked perfectly with El Capitan, and it started to freeze with Sierra.

The culprit seems the graphic card, because it freezes only when I launch games (and not intensive ones, like Civ5 for instance).

Any advice would be helpful.

Oct 31, 2016 11:05 AM in response to pacomedanhiez

Ok, I tried several things these 2 past days :

1 - Reinstall a fresh Sierra from usb

2 - Install minimal software : xCode, LittleSnitch, iStatMenu, Airmail, Steam and Civilization6 (for GPU stress-test)

3 - Use iStatMenu to monitor the CPU / GPU temperatures, and to increase the fan speed (minimum 2200 to keep everything cold)

Results :

1 - Coded several hours with xCode, programming intensive GPU usage with METAL => no crash.

2 - Played Civ6 during few hours, and my iMac froze 3 times :

After each crash, I had to unplug the electric, wait 10 seconds, plug it again, and then boot. Without that, my iMac didn't want to boot anymore.

==> First freeze : I was playing for 2 hours, then switched to Safari (while keeping the game opened), and it immediately crashed. The GPU was at 88 degrees, and CPU 55.

==> 2nd freeze : I restarted my Civ6 game, and I took care of not launching anything else in background. The mac froze after 1 hour. The GPU and CPU were still at acceptable temperatures.

==> 3rd freeze : Same thing..

Do you know which log files would be relevant to analyse in Console ?

I looked at some of them, but nothing exceptional..

Clearly, there is a problem with Sierra and hardware support.

This kind of "crash" is more a kernel panic due to bad driver implementation than a simple application crash.

Could have been a problem with Safari (a bug in the JIT implementation for instance, which could completely break the kernel), but it happens without launching Safari. Or maybe Safari is triggered in background without fully launching the process ?

Oct 31, 2016 11:39 AM in response to pacomedanhiez

I have been binging pretty hard on Civ 6 since release (over 40 hours played on iMac), the only time my Civ caused a kernel panic was when I was switching out to an app I think it was Messages. The cause of the kernel panic was marked as "Dock.app" so I figure, in my situation, games + switching screens cause kernel panics sometimes.

I haven't had any other issues with gaming on the iMac other than some (4-5) kernel panics due to switching screens when I have a game open. I usually play games like Civ 5/6 and Dota 2 pretty often on this device... but I never had real problems pointing to a faulty GPU - only sporadic crashes in weird instances like when the game is in the menu and I'm switching screens to Mail, Safari, Messages or something.

But the kernel panics that I've been having also point out to some bad driver implementation causing systemwide freezes in particular instances.

As for console reports, the best place to see these crashes is in: console > System reports (with all messages chosen) > and then look items labelled as "Kernel ..."

Late 2015 iMac 5K Freezing