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A few weeks ago my iMac 27" Mid 2011 started restarting by itself. After a further investigation I found that it wont start with 4 CPU cores, but max 3. Is it possible that my 4th core is dead?
Thank you!
Krasi
Posted 2013-05-25T09:33:11.797
Reputation: 1
I'm thinking it might also be a chipset/motherboard issue and not necessarily your CPU ? – None – 2016-07-21T22:03:40.330
Have you checked that there is not an issue with excessive heat? Such might (guessing) explain the symptoms. – Paul A. Clayton – 2013-05-25T09:38:38.183
Hi, Paul. Thanks for your comment! It happens even if the computer is completely cold. Also, I have opened it and cleaned all the dust (which wasn't that much as I expected). It's a weird problem, there is no debug in logs and it restarts 10-15 seconds after showing apple logo. – Krasi – 2013-05-25T09:42:36.263
2ockquote>
Is it possible that my 4<sup>th</sup> core is dead?
Yes, technically that is possible.
However I never heard of a single core dying before. CPU can die when mistreated. Pins can get bend. Static electricity can kill them. Cooling failures on older CPU's (P4 era) could kill a CPU quite quickly. But just one of four cores dying? I never heard of that happening. – Hennes – 2013-05-25T10:37:36.220
1You wrote that you cleaned all the dust. Did that cleaning include removing the heat sink? If you did, is it properly reattached with fresh thermal paste. I have a hard time imagining the heat sink just cooling one corner of the CPU and letting the other corner overheat, but it is the only think which seems reasonably likely. – Hennes – 2013-05-25T10:38:00.237
Hi Hennes. Thanks for your comment! I didn't remove the heat sink as I was afraid that I can break something. I've been opening and cleaning PCs, but an iMac seems to me as much more sensitive to touch inside. Should I try to remove the heat sink and clean again? – Krasi – 2013-05-25T11:01:01.207