I have a MacBook Air 2012 (A1466) and it developed some memory errors. It crashes every half hour and Apple Hardware Test says
4MEM/9/40000000: 0x79eea590
Unfortunately, RAM is soldered on the motherboard and it is not replaceable.
I did some research and found that it is possible to tell the operating system to ignore wrong memory addresses if you use Linux: Ubuntu Forums: Exclude Bad Memory
Is is possible to somehow exclude faulty RAM addresses in Mac OS X?
I currently use Yosemite (10.10) but, I am willing to downgrade if necessary.