iMac random restarts but no problems

Hippocrates1985

macrumors member
Original poster
Oct 13, 2008
40
2
hi guys,

I really need your help. I do not know what info do u want to know about my iMac. It's Mid 2011, 2.7 GHz intel Core i5 Processor, 32 GB Memory, and running Sierra.

Lately I have random restarts and I have done the Apple Diagnostic test and it has given me no hardware errors. I also used TechTool Pro 9 and the same thing with the results saying no errors at all.

I really need your help solving this puzzle.

Thank you
 

Fishrrman

macrumors P6
Feb 20, 2009
17,209
5,554
Have you added RAM?
Do you have the original RAM?
Have you tried reverting back to the factory RAM?
Have you tried re-seating the RAM in the slots?
 

Hippocrates1985

macrumors member
Original poster
Oct 13, 2008
40
2
Have you added RAM?
Do you have the original RAM?
Have you tried reverting back to the factory RAM?
Have you tried re-seating the RAM in the slots?
Thanks for the reply. I have taken all the RAMs out and put the original RAMs and nothing change. I still get the random restart. One thing weird thing that you might help me with is that I have moved all the files from this iMac to and external hard drive and now the iMac stays on longer than before. I thought that I have a problem with the hard drive but I have tested the hard drive with many applications and all of them says no error or problems with the hard drive. The fans are working good and no high temperature. Also I did format the hard drive and reinstall Sierra and the problem is still there :-(

I hope that you could help me in this puzzle and narrow down the problem because all the applications that I used saying that I do not have any hardware problems
 

ryguy92000

macrumors regular
Sep 20, 2014
111
19
Salt Lake City, UT
your graphics card is failing. 2011's are know to have this issue. If its not ram, its the GC. There is no 100% way to test the card as the issue is 'random'. Replacing the card will fix the issue
 

Hippocrates1985

macrumors member
Original poster
Oct 13, 2008
40
2
https://support.apple.com/en-us/TS3742

Are you getting the kernel panic screen like in the screenshots at this page?
yes I get that and to exact it's this pic

https://support.apple.com/library/content/dam/edam/applecare/images/en_US/osx/kernel_panic_symptoms_mtlion.png
[doublepost=1493118333][/doublepost]
your graphics card is failing. 2011's are know to have this issue. If its not ram, its the GC. There is no 100% way to test the card as the issue is 'random'. Replacing the card will fix the issue
Should be a way to test it ? I do not see any problems with the screen at all :-(

I mean you r not going to buy GC if you r not sure the the problem is really from GC
 

komatsu

macrumors 6502
Sep 19, 2010
472
34
Its actually quite unbelievable that nobody has brought out a software-based GPU tester / stress tester for OS X?
 

ryguy92000

macrumors regular
Sep 20, 2014
111
19
Salt Lake City, UT
yes I get that and to exact it's this pic

https://support.apple.com/library/content/dam/edam/applecare/images/en_US/osx/kernel_panic_symptoms_mtlion.png
[doublepost=1493118333][/doublepost]

Should be a way to test it ? I do not see any problems with the screen at all :-(

I mean you r not going to buy GC if you r not sure the the problem is really from GC
after working on these machines for 15 years its an either/or scenario. What is happening is the machine is expecting a certain data stream to move back and forth from the GC, when it doesn't get that information it will kernel and shut down. You can try stressing with an external OS, changing the ram, and replacing the HDD. These are all causes of this particular failure. However, your 2011 iMac is a known flaw with this GC. If you want to attempt to narrow it down, try accessing the kernel log for that time frame and dumping the kernel panics here. That may give us a better idea as to what is going on.