GPU Reset , GPU ASIC Log on Mac Pro with Dual AMD FirePro D700

GPU crashes on my Mac Pro. Please suggest how to fix the crash.

I run a workload that opens many windows. After an hour or two, the GUI freezes: I cannot focus on any window, cannot open "Force Quit" etc. However the mouse pointer still works, and I can ssh to the Mac Pro from a different computer.

I identified the following information that supports why I think it's a GPU crash. These pieces of evidence come from different crashes around the time when the crash occurred:

kernel[0]: ** GPU ASIC Log Start **

in /var/log/system.log

kernel[0]: [6:0:0] GPU HangState 0x0000000e, HangFlags 0x00000007: IndividualEngineHang 1, NonEngineBlockHang 1, FenceNotRetired 1, PerEngineReset 0, FullAsicReset 1

in /var/log/system.log

The windowserver was in the state "uninterruptible wait":

bash-3.2$ ps -ceo pid,ppid,stat,comm | grep Win

159 1 Us WindowServer

GPU Reset

in /Library/Logs/DiagnosticReports/ in Kernel_2015-10-09-125135_greg-mac-pro.gpuRestart

Exception Type: EXC_CRASH (SIGABRT)

Process: WindowServer [171]

in /Library/Logs/DiagnosticReports/ in WindowServer_2015-10-10-113109_greg-mac-pro.crash

The crash occurs reproducibly on my Mac Pro.

The spec of Mac Pro:

2.7GHz 12-core with 30MB of L3 cache

Dual AMD FirePro D700 GPUs with 6GB of GDDR5 VRAM each

64GB (4x16GB) of 1866MHz DDR3 ECC

I bought the Mac in September 2015.

I run Yosemite OS X 10.10.5 and El Capitan OS X 10.11, and in both cases the crashes occur reproducibly.

These kernel extensions (in /System/Library/Extensions/) relate the the crash, which I can see from stack traces reported is some crashes:

com.apple.AMDRadeonX4000

com.apple.kext.AMDFramebuffer

com.apple.kext.AMD7000Controller

com.apple.kext.AMDSupport

In Yosemite OS X 10.10.5 these extensions are version 1.3.2, and in El Capitan OS X 10.11 version 1.3.6.

The problem seems to be gone when I rename the extension files, so that the OS cannot load them. Unfortunately, then graphics becomes much slower (of course), and my workload consumes much more RAM (window data is probably in the RAM, instead of the VRAM of GPUs).

I called Apple Care, and they recommended SMC reset, PRAM reset and disk repair, which did not help. They also recommended going to an Apple Service Center for an inspection.

I saw some people suggest a GPU hardware issue, and the need for a replacement

http://forums.macrumors.com/threads/gpu-hang-state.1733147/

https://discussions.apple.com/thread/6439490

Also someone suggested that GPU crashes when too hot

https://getsatisfaction.com/apple/topics/2006_imac_graphics_card_crash_freeze