In my case problems persist also with sierra. On average (with moderate use of the mac) i have a freezing each 4 to 7 days, but in the last two days i made an intensive use of my mac pro (i followed some event in live streaming with chrome, meanwhile i had also firefox open on other sites and also at times I watched some music video on youtube with firefox). This has led to 4 or 5 crashes in two days, i cannot even count them precisely. It's like an overheating problem.
I've read this entire thread with a mixture of relief that I'm not the only one and despair that this problem will ever get fixed. I know that a few MacBook Pro users have weighed in too, so it's clearly not a problem limited to the Mac Pro, but I wanted to add my data point even though I'm on an iMac instead of a Mac Pro. It seems to me that that could be relevant information.
Here's my setup:
Model Name: iMac
Model Identifier: iMac17,1
Processor Name: Intel Core i5
Processor Speed: 3.3 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 24 GB
Boot ROM Version: IM171.0105.B09
SMC Version (system): 2.34f2
Chipset Model: AMD Radeon R9 M395
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 2048 MB
Vendor: ATI (0x1002)
Device ID: 0x6920
Revision ID: 0x0001
ROM Revision: 113-C905AA-799
EFI Driver Version: 01.00.799
Metal: Supported
Displays:
iMac:
Display Type: Retina LCD
Resolution: 5120 x 2880 Retina
Retina: Yes
Pixel Depth: 30-Bit Color (ARGB2101010)
Main Display: Yes
Mirror: Off
Online: Yes
Automatically Adjust Brightness: No
Built-In: Yes
Despite a different GFX card and obviously an entirely different machine, I have had similar experiences as so many people on the thread. For a while it was kernel panics, but then (presumably after some intervention on my part) it switched to the .gpuRestart problem. Spinning beachball, frozen UI, mouse pointer will move but won't interact with anything, leaving the machine usually (but not always) reachable by SSH.
In my case, a symptom that may not afflict the Mac Pro but certainly seems related to these issues is that most times when I log out or shut down, I get a weird neon-colored pattern of lines on my screen before it shuts off. I showed a pic to the Apple Genius but he didn't seem all that impressed/concerned.
Obviously in my case it can't be the specific type of display or connector that causes the problem.
I've recreated my entire user account from scratch, to no avail. I've tried removing third party RAM, unplugging from my APC UPS, unplugging peripherals (I have no Thunderbolt devices, just USB), reinstalling the OS, etc., etc. I'm currently on the latest public release of Sierra and my problems persist.
As with so many on this thread, I have found it impossible to isolate the cause of the issue in particular running software. I do run Adobe CC (but so do all my coworkers with iMacs who have no similar problems), and I have Safari, Mail, Messages, iTunes and iPhoto running pretty much nonstop while I'm using the machine.
I keep flailing about, sometimes thinking I've solved the problem by uninstalling something or shutting some third-party app down, but it always rears its head again. For me, it seems to happen most often when I'm screen sharing, but there are times it happens when I'm not.
Thanks to some tips on this thread, I'm going to try running without Flash installed and with Safari shut down unless I'm actively using it, and see if that seems to help.
I'd be willing to cross reference third-party software or Safari extensions to see if we all have something in common but that's just as quixotic, I know. Seems that people have had this happen even when running nothing but a fresh install.