Can a 2011 27” iMac run with internal hard drive disconnected?

[ares1849]

Hi, I recently bought a cheap 27 inch 2011 iMac just to mess with (and mostly use as an external monitor for some other Macs). I’ve read that the video cards can overheat in this model and removing the internal hard drive can help with thermal management. I’ve replaced hard drives with SSDs in these machines before, but this iMac has a built in 256 GB SSD and a 2 TB hard drive stock. Can I just remove the hard drive and run the OS from the factory SSD? Or will the fans run constantly without being plugged into a hard drive? I can replace the hard drive with an SSD, but I’d rather avoid doing so since this is a project machine/external monitor and one 256 GB SSD already is plenty. Thanks!

 

[Juicy Box]

If you feel comfortable with opening Macs, I would just give it a try. I have opened up the Mid 2011 iMac and replaced the drive in less than 10 minutes. While it would probably be safer to remove the LCD completely, I have swapped drives without disconnecting any of the connectors on the LCD, I just only lifted it a few inches and used a very short driver.

I am unsure if the fans will be affected by removing the HDD, but like I said, you could quickly open your iMac, but just disconnect the SATA cable plugs, leaving the HDD in, close everything up, and test it see if the fans get all messed up.

As for the fan, I have read that people with the Mid 2011 iMacs have had issues with the fans running full blast with the HDD swapped or removed, and some say that they did not have this issue.

I no longer have my Mid 2011 iMac, so I cannot test it, but either way, I suspect that it might depend on the specific iMac.

Maybe since yours came with a BTO SSD, you will not have the fan issue.

But, I would just try it. You can use iFixit's guide, but just stop at the part where you start disconnecting the LCD connectors, disconnect the HDD, put it back together, and see what happens.

I can replace the hard drive with an SSD

If you iMac is subjected to the max fan speed issue, just swapping the HDD for a SSD or another HDD will not correct the issue. Apple's OEM HDDs have built-in temp sensors, and most third-party HDDs or SSD do not have built-in sensors.

Usual solutions are using an external sensor or using SW to control the fan speed, but I have seen people just short/close the two wires leading to the HDD that are used for the temp sensor.

Swapping with a SSD or just removing the HDD and not replacing with anything would leave the two sensor wires open, which then leads the OS to run all the fans at full blast due to thinking the sensor went bad. This might not happen to your specific iMac, but you can easily check it.

I would just disconnect the HDD to see what happens.

 

[glenthompson]

There is software that can provide fan control. I use HDD Fan Control on my SSD equipped 2011.

 

[highvoltage12v]

With a 2011 iMac the Temperature signal wires are built into the Sata power connector, so you will probably have to add the OWC thermal sensor for 2011 iMacs to your Sata power just to stop the HDD fan from running full speed. You can also use software to slow down the HDD fan after login.

 

[dogslobber]

There is software that can provide fan control. I use HDD Fan Control on my SSD equipped 2011.

Yep, this. Been running Mac Fan Controls for five years across two 2011 iMacs.

 

[herrdude]

With a 2011 iMac the Temperature signal wires are built into the Sata power connector, so you will probably have to add the OWC thermal sensor for 2011 iMacs to your Sata power just to stop the HDD fan from running full speed. You can also use software to slow down the HDD fan after login.

Somewhere on these forums, someone suggests using a Y splitter which solves the problem too (@Ausdauersportier, I believe).

 

[ares1849]

If you feel comfortable with opening Macs, I would just give it a try. I have opened up the Mid 2011 iMac and replaced the drive in less than 10 minutes. While it would probably be safer to remove the LCD completely, I have swapped drives without disconnecting any of the connectors on the LCD, I just only lifted it a few inches and used a very short driver.

I am unsure if the fans will be affected by removing the HDD, but like I said, you could quickly open your iMac, but just disconnect the SATA cable plugs, leaving the HDD in, close everything up, and test it see if the fans get all messed up.

As for the fan, I have read that people with the Mid 2011 iMacs have had issues with the fans running full blast with the HDD swapped or removed, and some say that they did not have this issue.

I no longer have my Mid 2011 iMac, so I cannot test it, but either way, I suspect that it might depend on the specific iMac.

Maybe since yours came with a BTO SSD, you will not have the fan issue.

But, I would just try it. You can use iFixit's guide, but just stop at the part where you start disconnecting the LCD connectors, disconnect the HDD, put it back together, and see what happens.


If you iMac is subjected to the max fan speed issue, just swapping the HDD for a SSD or another HDD will not correct the issue. Apple's OEM HDDs have built-in temp sensors, and most third-party HDDs or SSD do not have built-in sensors.

Usual solutions are using an external sensor or using SW to control the fan speed, but I have seen people just short/close the two wires leading to the HDD that are used for the temp sensor.

Swapping with a SSD or just removing the HDD and not replacing with anything would leave the two sensor wires open, which then leads the OS to run all the fans at full blast due to thinking the sensor went bad. This might not happen to your specific iMac, but you can easily check it.

I would just disconnect the HDD to see what happens.

Thank you for the great reply, I will do so!

 

[Aesthetica]

Adding my perspective – I use a 2011 with Macs Fan Control - was worried it wouldn't work 100+% but it does. I completely forget its running - no need for hardware mods as far as I can see