This iMac was previously at an authorised Apple repair centre who cancelled the repair as parts to fix it were no longer available.
It is used every day at a printing company and runs a combination of MacOS and Windows.
The iMac was turning on but refusing to start MacOS. Even with our external USB Test SSD with MacOS installed it would always hang on a CPU Syncing error.
We then tried our Linux based diagnostics system which also halted on a CPU Error. Could it be a faulty CPU? Very rare and unlikely with Intel Desktop CPUs.
We ran a failsafe mode which disables the multi-core (Quad Core) Processes and forces the machine to only use a single core - It worked! We could then get into diagnostics and test the Ram and Hard disk which were fine.
So, the CPU has a faulty Core - an extremely rare fault.
This Machine is running an i5-4590 3.3Ghz CPU and to make good of the situation we decided to replace it with an upgraded i7-4790 3.6Ghz.
To upgrade the CPU we had to strip the iMac down completely and remove the logic board.
Modern iMacs after 2012 are very specialised as the LCD is bonded to the front glass which is only a few mm thick. The glass is then bonded to the aluminium frame. Taking the screen off is a very delicate procedure and if you have not done it before there is a very high chance of it cracking and being destroyed. You can't simply swap the glass like pre 2011 models.
Once the logic board is removed we removed the heatsink, applied fresh thermal paste and fitted the new processor.
While the logic board was out the company opted to remove the slow 160MB/s Hard Disk and Upgrade it to an NVMe SSD which can read at 3500MB/s. A phenomenal upgrade and as the NVMe socket is on the back of the logic board, well worth doing while it is out.
We only use the top branded SSDs which come with a 3-5 year hardware warranty for piece of mind.
As well as a speed improvement, SSDs are also Shock Proof, Quieter, Cooler and much more power efficient. Please check our
SSD Upgrade page for more information.
While the iMac was apart we cleared all dust and fluff from the casing and heatsink. The fan was stripped down, cleaned out and the bearings were lubricated.
The iMac Was then Rebult, All connections were cleaned with alcohol.
We partitioned and formatted the new NVMe SSD and freshly reinstalled it with MacOS High Sierra 10.13. This machine could take the latest MacOS but the company uses software that does not work with 64-bit OS Such as Catalina 10.12 and Big Sur 11.01.
Look at that new Spec; i7 3.6Ghz with 32GB Ram and a 1TB NVMe SSD.
Once Installed we completed all of the updates and then migrated all of the companies Data, Apps and Settings from the old hard disk onto the new NVMe SSD.
Once is was restored with all of the companies user data it was then time to set up the Windows virtual machine.
Looks promising, Windows is starting!
The die hard Apple fans won't be happy with this, but when you have Windows based machine software that has no Mac support its a great option.
Our customer was so happy, after being previously told that it is impossible to repair we have not only got it working but improved it to the point that it is lightening fast.
If you have an iMac which is no longer powering on or is sluggish please get in touch. We regularly perform SSD upgrades in 2008 - 2020 iMacs and give them a whole new lease of life.
