With macOS 10.13, otherwise known as High Sierra, Apple introduced an ambitious EFI update. Several of the changes include: the introduction of the Apple File System, support for NVMe drives, and the usual batch of security updates. However, these EFI updates can cause some unwanted behavior when you test your Apple computer’s memory. At Beetstech, we use a long-time industry standard, MemTest86 to perform a comprehensive test of each computer’s RAM.
But never the type to blindly accept test results, strange testing outcomes led us to discover a bug in MemTest86 affecting computers running the new EFI firmware. In short, the newly updated EFI causes MemTest86 to incorrectly fail certain tests. But there is good news: while normal operation of MemTest86 is limited under these new EFI updates, we also discovered some simple workarounds for testing your Apple’s memory in MemTest86.
So let’s dive into how we discovered the MemTest bug, devised a reliable work-around, and get into some nitty gritty details of MemTest86 operation.