iMac 27 5K 经常在睡眠的时候自动重启是怎么回事？ 又遇到同样问题的吗？

17 年底买的 iMac 27 5K
最近总是在睡眠模式下自动重启， 看日志好像和 GPU 有关， 是硬件问题还是软件问题， 这问题似乎是从今年 6 月开始出现的

今天凌晨的日志
Aug 27 00:33:51 Ashong-iMac syslogd[41]: ASL Sender Statistics
Aug 27 00:34:01 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 1 seconds. Pushing respawn out by 9 seconds.
Aug 27 00:34:10 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Aug 27 00:34:32 --- last message repeated 1 time ---
Aug 27 00:34:32 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 1 seconds. Pushing respawn out by 9 seconds.
Aug 27 00:34:51 --- last message repeated 1 time ---
Aug 27 00:34:51 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Aug 27 00:35:12 --- last message repeated 1 time ---
Aug 27 00:35:12 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 1 seconds. Pushing respawn out by 9 seconds.
Aug 27 00:35:21 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Aug 27 00:35:37 --- last message repeated 1 time ---
Aug 27 00:35:37 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.quicklook[14031]): Endpoint has been activated through legacy launch(3) APIs. Please switch to XPC or bootstrap_check_in(): com.apple.quicklook
Aug 27 00:35:42 Ashong-iMac com.apple.xpc.launchd[1] (com.apple.DumpGPURestart): Service only ran for 1 seconds. Pushing respawn out by 9 seconds.
Aug 27 00:42:06 localhost bootlog[0]: BOOT_TIME 1535301726 0
Aug 27 00:42:14 localhost syslogd[41]: Configuration Notice:


又遇到同样问题的吗？