Memtest OSX is the best ram-testing utility for the Macintosh platform with the ability to find intermittent memory problems that are the frequent cause of unexplained crashes or freezes in Macs. Memtest can identify random memory problems that commercially available utilities miss completely including defective motherboard CPU cache memory.

This small command-line utility thoroughly checks available memory under OS X. Memtest is licensed under the Gnu Public License and is distributed with source code. This program was originally authored by Charles Cazabon for Linux platforms. The MacOS X port is maintained and enhanced by Tony Scaminaci.

Memtest is distributed as a universal (fat) binary containing four separate executables, targeting each of the major classes of available Macs. The appropriate machine-specific executable is loaded by OS X at launch time.

Memtest executes in 64-bit mode on PPC G5, Intel Xeon-based Mac Pros, and the latest Macbook Pro Core 2 Dual systems running MacOS 10.4 or later, allowing virtually any amount of installed ram to be tested. On all other systems, memtest executes in 32-bit mode with a maximum testable limit of 2 GB.