Chosen Solution
Hello, so my late 2013 iMac was running a little slow in the past few months therefore I decided to format its hard drive and do a clean Catalina OS install. All went fine until the OS installer failed to complete the task and gave an error that it was unable to do so. After a few tries hoping it was some internet flaw it became clear that something was up. So I did a diagnostics test on boot and got no error code at first, which was odd. After a lot of tries and confusions I repeated the diagnostics test, finally showing an error code: PPM003. After looking on AHS code references it showed that was a “failure at integrated memory level”. That got me confused cause that iMac doesn’t have inboard memory as far as I know but anyway. So I brought the computer to an apple service provider so they could swap the memory modules and see if it worked. The technician that worked on my iMac said that it was the hard drive that showed that it was worn down so that I should swap to an SSD. I said ok since it was something I wanted to do anyway. After that he reran the AHT tests which still showed the PPM003 error plus he said the computer was indeed slow on boot which was odd considering the new SSD. Then he ran the tests with their in-house new memory modules which still showed the error. I told him to do the test testing separate memory modules in case it was only a single one at fault and still showing the same. So now he doesn’t know what to do and neither do i. So after all that I wanted to ask. Could this be a logic board problem or is apple diagnostics messing up? Sorry for the essay but I really like this computer and want to get it fixed.
@gu_voss - You clearly have a SMC error condition! The system is in CPU safe mode, basically the CPU’s clocking is reduced and the fan ramps up. As to why this is happening is do to the loss of a critical sensor! Let me explain… Apple contracted custom HDD & SDD’s which expose the drives internal thermal sensor for SMC to access so it can monitor the drives heat. So your friend took the HDD out putting in a SDD in its place but… The SSD he put in is not running the custom Apple firmware (as its not an Apple drive) or one of the newer S.M.A.R.T. drives which have the updated ability for the system to access the drives thermal sensor. Apple Petitioned the standards to offer a better means to access the thermal sensor. The older method required a IRQ request which doing once and awhile is not big, but Apple is calling it every ten secs or so. This would in turn slow your system down big time! Remember Apple uses custom 3.5” HDD’s in the 27” systems and they face the same problem! But Apple never altered them as it was less of an issue as there was a spare SATA port so a dual setup could be used leaving the HDD in place working or not! So your solution is getting a currently manufactured SSD which has the newer S.M.A.R.T services.
