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The Problem
The most often reported symptom is a lockup of the Mac Pro with a spinning beach ball. Audio often continues uninterrupted. The user is unable to recover control of the Mac Pro by any keyboard action, and holding down the power button until the Mac shuts down is necessary. Upon power up, all seems normal. The problem happens sporadically, sometimes several times a day and sometimes doesn't happen for weeks at a time. That is my own experience.
Possible Culprit
The community appears to concur that this is a graphics card issue or an internal bus issue. Inspection of the Console log file by customers has revealed several different errors, but the most common are:
Kernel_2015-xx-xx-xxxxxx_Mac-Pro.gpuRestart
or…
PM WindowServer: GPU Driver appears to be hung (over 5 continuous seconds of unreadiness)
Forum Discussion
An exhaustive discussion of the problem appears in this forum. “Mac Pro (Late 2013) GPU (Driver) Issues.” The discussion spans over a year, 29 pages and 702 posts.
What Doesn't Help
Many of the postings describe historical attempts to fix the problem in various ways. Here are things mentioned that do not consistently work.
- Upgrading to OS X El Capitan from Yosemite.
- Removing non-Apple applications.
- Doing a clean install.
- Getting a replacement Mac Pro or new graphics cards (D300 only)
- Using the HDMI port instead of TB/DisplayPort.
- Changing out the miniDisplayPort to DisplayPort cable.
- Changing displays.
Generally, before the Repair Extension Program described next, when customers took their Mac Pro, under warranty or Apple Care, to an Apple retail store, it passed all the hardware tests, leaving the customer frustrated. On several occasions, hardware was replaced (before the REP), and after a period of time, the problem resurfaced.
Apple's Replacement Program
In early February, 2016, MacRumors obtained an Apple internal notice that discussed a Repair Extension Program (REP):
Apple has determined that graphics cards in some late 2013 Mac Pros, manufactured between February 8, 2015 and April 11, 2015, may cause distorted video, no video, system instability, freezing, restarts, shut downs, or may prevent system start up.
Apple or an Apple Authorized Service Provider will repair eligible Mac Pro models affected by the video issues free of charge until May 30, 2018. Apple lists a turnaround time of about 3-5 days.
Apple says both graphics cards must be replaced on Mac Pros exhibiting any of the problems listed above. AMD's FirePro D500 (high-end model) and D700 (built-to-order) GPUs are affected. AMD's FirePro D300 GPU on the base Mac Pro is not listed.
A Workaround
Many of the postings to the above forum describe how turning off the external display(s) or disconnecting the video cable and reinserting allows the user to regain control of the Mac. This presumably restarts the graphics driver. Most often, the Mac operates very sluggishly after this, and, with patience, the user can then conduct a graceful reboot. That returns the Mac to normal speed.
I have used this technique, and it usually works.
Another occasionally mentioned technique is to use an SSH client to connect to the Mac and issue a reboot command. There are even iOS SSH clients that can be used. Remote Login must be enabled in System Preferences > Sharing. Additional details are beyond the scope of this article.
Theories
The unpredictability of this event has made it hard to diagnose. I have had it happen most often in Safari (which I don't use anymore) and even in the Mail App once. Other apps in use when the Mac Pro froze were Chrome browser with Google Hangouts and Skype. (The Mac Pro I use has AMD D300 FirePros.) Amazingly, the audio survives the spinning cursor and GUI freeze-up.
From my reading of the forum posts above, the problem might be a design flaw in the Mac Pro's internal bus that fails under heavy graphics load. I don't recall the problem with OS X Mavericks with which the machine shipped. It did start in Yosemite, which suggests that some graphics feature of later OSes surfaces the bug, but only occasionally. That's just a theory.
Synopsis
Apple has no known repair program for the Mac Pros with the D300 FirePros, and evidence from user conversations with Apple suggests that that the root cause remains unknown. No one seems to know why the D300 wasn't also covered in the REP. I recommend that System Preferences > Security & Privacy > Privacy > Diagnostics & Usage be enabled so that Apple engineers can log and perhaps diagnose the magnitude of the problem.
Right now, without direction from Apple for the D300 users, the problems continues, leaving many Mac Pro customers frustrated in their ability to conduct mission critical work on a reliable basis. It also seems to be souring customers on the both the quality of this flagship product and the ability of Apple's customer service to deal with the problem. The only solution may be to wait for Apple to release a next generation Mac Pro, recycle the old one, and hope that more modern hardware and Apple's engineering experience have solved the problem for good.
If we hear back from Apple, I'll update this article.