Mid – 2011 iMac 27” heard overheating episode with the fans roaring.
Never a problem with this mid – 2011 iMac, one which I placed 2 internal 128GB SSDs and removed the optical drive. Never a problem and iStat Menus, which I purchased years ago, always showed the three fans running at normal optimal speeds around 1000 RPM. The other night, heard a relatively loud whirring sound coming from the computer table. There are two 27” iMac’s, 2011 and 2014, and finally realized it was coming from the right side of the 2011 iMac, the side I remember where the optical drive is located. iStat Menus showed the sensors with an episode of relatively high temperatures and high fan speeds, ~ 1,700, checked the seven day and 30 day history, clearly showing a rapid rise in temperature in fans speeds lasting short period of time. Restarted the computer and everything returned to normal quickly. I did eliminate two apps that came with my Seagate drive, an 8 terabyte which I had recently installed. I thought that might have been the problem, since it seem to return to normal, and Mac cleaner app removed a tremendous amount of accessory files. However the optical fan seems to be malfunctioning, showing zero RPM or 143 RPM, and a 24 hour history showing speeds under 100 RPM. In the past it’s always been around 900 to 1000 RPM.
In a few searches the issue of dust came up and this is something I have never done. Getting conflicting advice as to vacuuming and compressed air accessing the slots on the top, sides and bottom, as well as the RAM cover.
I had no problem, though quite tedious with the kit and two suction cups installing the SSDs, one from OWC and the other OCZ - both 128 GB, along with the internal 1 TB Western Digital. I would dread taking the computer apart again, but the dust that must have accumulated and the probable cause of the overheating slightly. The optical drive fan was functioning normal for several hours after the 1700 RPM episode, but then iStat Menus showed that fan running at either zero RPM or 143 RPM. So I have two questions, is the Optical Drive fan gone bad, and is there a way to test using iSTAT menus fan edit option; and, two would vacuuming or compressed air be sufficient to clean the dust from nearly a decade? The computer as nearly always on, although I have shut it down for now. I dread the idea of having to takeoff the front panel which was not a fun job , but I’m wondering if I need to replace a fan and a thorough cleaning and dusting? What are their current recommendations for dusting that particular model mid – 2011 iMac 27”, series 12,2 from System info? I like to use that computer while they Big Sur – 2014 is doing a task and from which I run LogicPro with audio interface. I don’t see any way to clean or dust that model, but the older model which is quite a bit thicker has those slots and other access points like the optical drive slot. Any advice would be much appreciated. Best, Seth
