MemTest86

MemTest86 is a standalone memory testing utility for x86-based computers. It runs from a bootable medium such as a USB flash drive or CD/DVD and does not require an operating system. The program exercises the computer’s random-access memory with a suite of diagnostic patterns and access sequences, and reports any errors with the corresponding memory addresses. Its goal is to identify defective RAM modules or memory controllers that cause data corruption.

The project originated as a DOS-based tool developed by Chris Brady in the 1990s. A community fork, MemTest86+, arose from the original work, and in recent years the official MemTest86 software has been maintained by PassMark Software, with support for modern hardware and firmware environments including UEFI. The tool is designed to work across a range of systems and memory configurations; on compatible systems it can test RAM that uses ECC.

Usage typically involves creating a bootable MemTest86 drive, booting the target computer from it, and running one or more passes of the test. The test suite is configurable and can be left running to increase detection chances; test results are displayed on-screen and optionally logged to a file. A single error is usually sufficient to indicate defective memory.

Limitations include that MemTest86 detects faults but does not repair them and false negatives can occur in some configurations. It is commonly used by technicians and hardware enthusiasts to diagnose RAM problems when a computer exhibits instability, crashes, or data corruption.