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Memtest86 9.4 Build 1000 by PassMark Software

Memtest86 9.4 Build 1000 by PassMark Software
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Memtest86 by PassMark is a comprehensive, free, stand alone memory diagnostic software It is designed to stress test an x86 compatible computer’s random access memory (RAM) for errors.

MemTest86 boots from a USB flash drive and tests the RAM in your computer for faults using a series of comprehensive algorithms and test patterns. It tries to verify that the RAM will accept and correctly retain arbitrary patterns of data written to it.

Memtest86 writes a series of test patterns to every memory address, reads back the data written, and compares it for errors. Using the information about the chipset you can enhance these tests – particularly in an overclocked system.

PassMark Memtest86 Main Features:

  • 13 different RAM testing algorithms
  • DDR4 RAM (and DDR2 and DDR3) support
  • XMP – high performance memory profiles
  • UEFI – The new graphical standard for BIOS
  • 64bit – From version 5, MemTest86 is native 64bit code
  • ECC RAM – support for error-correcting code RAM
  • Secure boot – With MemTest86 being code signed by Microsoft
  • Graphical interface, mouse support and logging of results to disk
  • Foreign language support (Chinese, German and more)
  • Self booting off USB, without needing DOS, Linux nor Windows
  • Network (PXE) boot – Scalable, disk-less provisioning from a single PXE server

Unreliable RAM can cause a multitude of problems. Corrupted data, crashes and unexplained behaviour. Bad RAM is one of the most frustrating computer problems to have as symptoms are often random and hard to pin down. MemTest86 can help diagnose faulty RAM (or rule it out as a cause of system instability). As such it is often used by system builders, PC repair stores, overclockers and PC manufacturers.

The number 86 following the MemTest part of the name, refers to the original x86 CPU instruction set that all of today’s PCs use. This covers both 32-bit and 64-bit machines. (So there is no need for a future product called MemTest64).

Free, Professional or Site Edition

Since MemTest86 v5, the software is offered as a Free edition, or as a paid for Pro and Site edition. The Pro edition offers a number of additional features such as customizable reports and automation via a configuration file. The Site edition includes all features in the Pro Edition but also supports scalable deployment of MemTest86 across LAN via PXE boot.

MemTest86 supports booting from the newer UEFI platform.

When booting from UEFI, MemTest86 has access to additional services not available in BIOS including:

  • Native 64-bit support
  • No longer requires the use of the PAE workaround to access more than 4GB of memory. (PAE = Physical Address Extension)
  • Mouse support, where supported by the underlying UEFI system. On older systems a keyboard is still required.
  • Improved USB keyboard support. The keyboard now works on systems that fail to emulate IO Port 64/60 correctly. So Mac USB keyboards are now supported.
  • Improved multi-threading support, where supported by the underlying UEFI system.
  • Reporting of detailed RAM SPD information. Timings, clock speeds, vendor names and much more.
  • Support to writing to the USB drive that MemTest86 is running from for logging and report generation. In all prior MemTest86 releases, there was no disk support.
  • Use of GPT. (GUID Partition Table)
  • ECC RAM support (limited hardware support, ongoing development)
    • Detection of ECC support in both the RAM and memory controller
    • Polling for ECC errors
    • Injection of ECC errors for test purposes. (limited hardware only)
  • Support for DDR4 RAM (and associated hardware), including retrieval and reporting of DDR4-specific SPD details. This includes DDR4 RAM that support Intel XMP 2.0 DDR4 RAM timings
  • Option to disable CPU caching for all tests
  • Support for Secure Boot.
  • Speed improvements of between 10% and 30%+. Especially for tests, #5, #8 & #9. This is the result more moving to native 64bit code, removing the PAE paging hack, switching compilers and using faster random number generation algorithms.
  • Addition of 2 new memory tests to take advantage of 64bit data and SIMD instructions.
  • Support for network PXE boot for scalable, diskless deployment to multiple targets

Changes in Memtest86 9.4 Build 1000:


  • Added new config file parameter, ‘MAXCPUS’, for setting the maximum number of CPU logical cores used for testing. By default, this value is 256 (Pro Edition) and 16 (Free Version). This parameter can be set to a maximum value of 512.
  • Added new config file parameter, ‘AUTOPROMPTFAIL’, for specifying whether to display the test result and ask for user intervention on test failure, even when AUTOMODE is enabled
  • Added new config file naming convention allowing for separate config files depending on memory size: <Memory-size-in-GB>GB-mt86.cfg
  • Fixed memory size calculation to use rounding instead of truncation
  • Display PASS message box in yellow (instead of green) on test completion if corrected ECC errors were detected
  • Display error message if no valid SPD.spd file was found when SPDMATCH=1
  • Display error message if no SPD modules were detected when SPDMATCH=1
  • Display error message and exit MemTest86 when failing to measure CPU clock speed during startup
  • Updated XML message to include CPU info & SMBIOS info sent to PXE server/management console
  • Added ECC Support for Intel Tiger Lake H chipset
  • Added ECC Support for Intel Rocket Lake chipset
  • Added ECC Support for Intel Alder Lake chipset
  • Added ECC Support for Intel Ice Lake-SP chipset
  • Added support for retrieving CPU info for Intel Elkhart Lake chipset
  • Added support for retrieving DIMM temperatures (TSOD) for Intel Alder Lake chipset
  • Fixed issue with measuring ARM64 CPU clock speed due to CPU cycle counter (PMCCNTR) being disabled
  • Fixed HTML report to display error bit map in text when copying/pasting
  • Fixed Linux badram entries in HTML report to be page size aligned (4096 bytes)
  • Fixed parsing bug with SPD.spd file when whitespace appears at the end of each line
  • Fixed issues with displaying RAM SPD DDR5-specific info
  • Fixed support for limited number of command line parameters in Free version
  • Fixed bug in overflowing text in SPD info screen
  • Fixed REPORTNUMWARN config file parameter not being written when saving config file
  • Included Serva PXE server configuration file in Site Edition package
  • Updated blacklist with Dell Precision 7760 screen display issues

Changes in Memtest86 9.3 Build 1000:


  • Support custom test definitions specified by a configuration file. A custom test definition consists of an existing test algorithm, specific test pattern, cache settings, and number of iterations. Custom test definitions are enabled by specifying the TESTCFGFILE parameter (Pro Edition only)
  • Fixed incorrectly formatted XML Status/TestResult files sent to PXE/TFTP server (Site Edition only)
  • Fixed incorrect reporting of error endianess for 128-bit test
  • Fixed bug in displaying/logging ECC error channel/slot number
  • Fixed report/log files not being saved correctly for non-standard USB flash drive installs
  • Improved responsiveness of pattern string updated on screen
  • Display row hammer warning, if applicable, in test completion popup message
  • Fixed ECC error reporting on AMD Ryzen chipsets to include channel/slot information
  • Fixed ECC error reporting on AMD Ryzen chipsets with 8 memory channels
  • Improved robustness of ECC error reporting for Intel Atom C2000 chipsets
  • Fixed retrieval of DDR4 SPD bytes on Intel Alder Lake chipsets
  • Added support for parsing DDR3 Module Manufacturer’s Specific Data
  • Updated blacklist with additional Surface Pro models with display issues

Changes in Memtest86 9.2 Build 2000:

  • Added large PASS/FAIL block text to top-right corner of HTML report
  • Added visual representation of bit error mask to HTML report
  • Fixed missing timestamp for ECC errors in HTML report
  • Fixed incorrect version string indicating “V9.1” instead of “V9.2”

Changes in Memtest86 9.2 Build 1000:

  • Preliminary support for retrieving and decoding DDR5 SPD data. This includes support for the new SPD HUB I2C/I3C command set.
  • Support for retrieving DIMM temperatures (TSOD) for AMD Ryzen chipsets
  • Fixed ECC error polling on Ryzen with multiple controllers
  • Fixed ECC detection on AMD Ryzen chipsets (Family 17h Model 31h)
  • Improved formatting of the Test Summary screen on test completion
  • Moved “RAM Temp” to “Pattern” line to allow longer RAM info display
  • Updated blacklist with additional baseboards with known multiprocessing issues
  • Refactored code for newer EFI Development Kit (EDK II) release compatibility

Changes in Memtest86 9.1 Build 1000:

  • Fixed parsing of SMBIOS memory device structure for compatibility with DDR5 DIMM data
  • Fixed non-page aligned addresses for ADDRLIMLO/ADDRLIMHI configuration file parameters
  • Fixed hang when running in UEFI Shell caused by improper cleanup of localization strings after an exit from a previous MemTest86 run.
  • Added support for retrieving CPU info for Intel Rocket Lake chipsets
  • Added support for retrieving CPU info for Intel Tiger Lake chipsets
  • Fixed misalignment of text containing full-width characters

Homepage –

System Requirements:

  • x86 based hardware, 32bit or 64bit
  • UEFI platform firmware
  • Windows, Linux, or Mac OS
  • USB Flash Drive (>= 512MB capacity)


  • IMPORTANT: MemTest86 V8 images support only UEFI boot. On machines that don’t support UEFI, MemTest86 will not boot. Please download the older V4 BIOS release of MemTest86 instead.
  • Installation and usage instructions are available on the Technical Information page
  • MemTest86 is a stand-alone program that does not require or use any operating system for execution. The version of Windows, Linux, or Mac being used is irrelevant for execution. However, you must use either Windows, Linux or Mac to create a bootable USB drive.