I have a late 2012 27" iMac running El Capitan (10.11.5). It is a 3.2 GHz i5 with 32GB of 1600MHz DDR3, 3TB fusion drive. It's worth noting that as of right now I can't get Graphics/Display information from the System Info tool.

While using the the mac, it randomly powers off. It will not power on again until I have unplugged it for a minute or two.

Within the last 6 months, Apple Genius techs have replaced:

• Logic Board
• Harddrive
• power supply
• Power supply connector cable (not sure what this actually is).
• GPU? I don't remember if this replaced this, but one of the last times I had it serviced they deliberately ran a graphics 'stress test' for a few hours before letting me pick it up again and the test came out fine.

Here is a portion of my Console log right before the last startup:

http://pastebin.com/raw/5NKKMkA1

My GPU has been restarting a lot recently as well. I can provide more from the gpuRestart kernel logs if necessary.

How do I trouble shoot this issue? I don't see any errors in the Console logs and when the mac starts back up, there is no dialog indicating that it knows it recovered from an error.

Other notes:

• Hardware check was clean.
• Identical mac plugged in on the same surge protector and not having issues.
• Bluetooth is disabled.
• I am using a USB mouse, keyboard and headset.
• My mac 'otherwise' feels healthy - nice graphics when playing a game, no UI slowness in other apps, wifi is fast. I/O is fast.
• I am the only user on this mac, other than the guest account.
• I cannot correlate shutdowns to running any specific program. I have changed from using Chrome to Safari with no luck. I have been running nothing but Finder when crashes happen. I have also been playing games when crashes happen.

I am trying to debug this myself after countless sessions with Apple support repeating the same steps for an hour only to get to a point where they ask me to take it in to a Genius appointment only to have them say they can't reproduce it.

I have a late 2012 27" iMac running El Capitan (10.11.5). It is a 3.2 GHz i5 with 32GB of 1600MHz DDR3, 3TB fusion drive. It's worth noting that as of right now I can't get Graphics/Display information from the System Info tool.

While using the the mac, it randomly powers off. It will not power on again until I have unplugged it for a minute or two.

Within the last 6 months, Apple Genius techs have replaced:

• Logic Board
• Harddrive
• power supply
• Power supply connector cable (not sure what this actually is).
• GPU? I don't remember if they replaced the GPU, but one of the last times I had it serviced they deliberately ran a graphics "stress test" for a few hours before letting me pick it up again and the test came out fine.

Here is a portion of my Console log right before the last startup:

http://pastebin.com/raw/5NKKMkA1

My GPU has been restarting a lot recently as well. I can provide more from the gpuRestart kernel logs if necessary.

How do I trouble shoot this issue? I don't see any errors in the Console logs and when the mac starts back up, there is no dialog indicating that it knows it recovered from an error.

Other notes:

• Hardware check was clean.
• Identical mac plugged in on the same surge protector and not having issues.
• Bluetooth is disabled.
• I am using a USB mouse, keyboard and headset.
• My mac 'otherwise' feels healthy - nice graphics when playing a game, no UI slowness in other apps, wifi is fast. I/O is fast.
• I am the only user on this mac, other than the guest account.
• I cannot correlate shutdowns to running any specific program. I have changed from using Chrome to Safari with no luck. I have been running nothing but Finder when crashes happen. I have also been playing games when crashes happen.

I am trying to debug this myself after countless sessions with Apple support repeating the same steps for an hour only to get to a point where they ask me to take it in to a Genius appointment only to have them say they can't reproduce it.