Chosen Solution
Hello, My iMac is making weird clicking/ticking noises. Thought it was the hard drive, so I put in an SSD, and went ahead and upgraded memory to 16GB, which didn’t solve the problem. I can reproduce the sound by running a GPU benchmark, or just opening every app, and will continue for up to 60 seconds after I shut down and unplug the machine. Thought it was the power supply, but I replaced that and still clicking. I don’t think it’s the fan because I can spin it up to 2800 rpm with smcFanControl, and it has no effect on the sound. Spinning up the fans doesn’t cause the sound to speed up or slow down, or change in any way. I don’t think it’s the speakers because if it was, the sound should stop the second the machine shuts down, or at the very least the second it is unplugged, but the noise persists. I’m out of ideas. I just want the clicking to stop, and I don’t know what to fix that will make it stop. Here’s a link to a video of the noises the computer is making. This is a video I took of this specific machine. https://streamable.com/mcj0m
Your hard drive is starting to die create a backup ASAP, so you don’t lose any of your data.
Lets try this reboot your system and hold the Shift key to get into Safe Mode. See if the clicking stops then. If its still happening lets try just starting up in Target Disk Mode holding the T key. The idea here is to pull away different parts of the OS to see what element is the source. In the case of Target Display Mode we are only running off of the systems BIOS kernel (EFI) no OS software is being loaded. Let us know what you discover! Reference: Mac startup key combinations Update (08/17/2018) Here’s the IFIXIT guide to replace the power supply: iMac Intel 21.5" EMC 2638 Power Supply Replacement and here’s the needed part: iMac Intel 21.5" (Late 2012-2019) Power Supply. you do need to be very careful when removing the display. Make sure you use the pizza cuter tool and picks. And don’t forget to order the adhesive strips (I would get two sets just in case!)
Did you ever find out what caused the ticking noise? Same thing is happening with my iMac 27”… but not constant… does it for a little while… then not at all for a day… almost sound like some type of relay switching on and off?
do you have a random shutdown issue? is it a late 2012 27inch imac?
After saying I’m also having this issue, I figured it out. Your GPU is overheating. The heat sync inside only covers the CPU, so your GPU is exposed and basically on its own. My advice is to download Mac Fan Control, then set the censor to your GPU, and set the threshold for about 72 C. I’m actually considering modifying the casing to allow fresh air in. That’s the main design flaw with these models.
