iMac keeps randomly restarting: HDD previously changed

A while ago I changed my internal HDD in my iMac (see below for specs) to a Seagate SSHD 7200RPM 2TB SATA 600 64MB HYBRID for a bit of extra room, and also upgraded the ram to 16GB.

Since then I've been getting periodic restarts (every two days at least, and often multiple times during the day) with no error messages that I can see or crash logs to point me in the right direction (that I know of).

I don't know if any of these are related, but does anyone have any suggestions as to the problem, or what specific logs I should look at to diagnose the problem?

Cheers


System: iMac (21.5-inch, Mid 2011), 2.8 GHz Intel Core i7, 16 GB 1333 MHz DDR3, AMD Radeon HD 6770M 512 MB

Welcome to our forums.

Your iMac came from the factory with a special proprietary hard drive and connector for its heat sensor. Unless you either replaced it with an Apple drive with the same connector and heat sensor or compensated for it, the hard drive fan will rev up and may cause kernel panics. (sudden restarts) The Seagate drive you used very likely is the cause of your restarts. I'm familiar with your iMac because I owned one just like it and had to replace its hard drive after the one it came with failed. However, in my situation the machine was covered under warranty and Apple replaced it.

Further to the Administrator's advice Hybrids did not have the best of runs on Macs. You needed to research this before taking the iMac apart. However OWC sell a special cable to overcome the lack of the heat sensor.


https://eshop.macsales.com/item/OWC/DIDIMACHDD11/

Hi chscag, thanks for the reply

I followed the install instructions from 'mac upgrades' and they originally suggested that I install this HDD fan control app which, I thought, should have helped this. I think though, going by what you said, it's probably not working as it should!

Thanks for that. I've just ordered one now; hopefully it will spare me the expense of a solid-state drive replacement!

harryb2448 said:

Further to the Administrator's advice Hybrids did not have the best of runs on Macs. You needed to research this before taking the iMac apart. However OWC sell a special cable to overcome the lack of the heat sensor.


https://eshop.macsales.com/item/OWC/DIDIMACHDD11/

Click to expand...

Don't use fan control apps as your iMac is designed to handle that.

harryb2448 said:

Don't use fan control apps as your iMac is designed to handle that.

Click to expand...

Except for those Macs that just run too **** hot and I have encountered too many of those.

When one can't rest their hand on the top left of an iMac, it's too hot IMHO and electronics don't last long in a high temperature. Period, regardless of what Apple's OS X settings are set for.

When one can't rest their hand on the top left of an iMac, it's too hot IMHO and electronics don't last long in a high temperature. Period, regardless of what Apple's OS X settings are set for.

Click to expand...

Generally iMacs run cool because of the way they're vented. If an iMac is too hot to the touch like you say above, then there's a problem with either the intake - exhaust vents at the bottom - top or fan related. Up until 2011 iMacs (both 21.5" and 27" models) were equipped with three fans. From 2012 on to the present, there is only one fan and the exhaust vent was moved from the top to the backside right below the top of the stand.

So Patrick why one would promote SMCFanControl and such which limit the fan speed when people do not follow instructions for replacing the hard drive? Fan controls accentuate the heating problem by limiting the speed.

I have never used nor promoted SMCFanControl, and have found the opposite that a proper fan control will not limit any fan speed below their set default speed.

I do recommend Macs Fan Control with it's various speed options, all of which are the default or higher speed.

http://www.crystalidea.com/products?source=fancontrol_mac






- Patrick
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You missed the 'and such'.

Just leave it to Apple - regardless what you think of them they are the experts.