Is memtest86-usb a Virus?
✔ NO - Safe
Provided by PassMark Software; run from legitimate USB media
Warning
Test results may indicate RAM faults
Hardware issues, not malware
Can I Disable?
✔ YES
To stop testing, remove the USB and reboot, or use BIOS to skip USB boot
What is memtest86-usb?
MemTest86-usb is a bootable memory diagnostic tool that runs directly from a USB drive, bypassing your operating system to thoroughly test RAM integrity. It boots into its own environment, executes a series of predefined memory tests, reports errors, and helps identify faulty modules or configurations. It supports both legacy and UEFI boot modes and provides optional stress tests.
MemTest86-usb uses deterministic memory patterns and parity checks to exercise RAM across addresses. It performs multiple passes, detects faults via pattern mismatches, and reports the specific failing address, bit, and pattern. It runs outside the OS to reveal hardware faults that software tests may miss.
Quick Fact: MemTest86-usb boots independently of the OS, performing a thorough RAM check that is useful for diagnosing intermittent crashes and memory-related errors.
Types of MemTest86 Tests
- Memory Pattern Tests: Different bit patterns test for stuck bits and pattern sensitivity.
- Address Range Tests: Systematic checks across memory addresses to detect addressing faults.
- Bit Spread / Walking Ones: Tests for single-bit and multi-bit errors across the memory array.
- Cache/Controller Stress: Stress tests on memory controllers and caches to reveal timing-related issues.
- Extended/Long Runs: Optional longer passes to increase fault detection likelihood.
Is memtest86-usb Safe?
Yes, memtest86-usb is safe when downloaded from official sources (memtest86.com or PassMark) and used as intended to diagnose RAM.
Is memtest86-usb a Virus or Malware?
The real memtest86-usb is NOT a virus. Malware masquerading as memtest86-usb is possible; verify the source, hash, and official publisher.
How to Tell if memtest86-usb is Legitimate or Malware
- File Location: Check the boot media for memtest86-usb.img at E:\ or memtest86-usb.iso at F:\ on the USB root. A legitimate image should exist at one of these locations.
- Hash Verification: Compare the downloaded image's SHA256 with the official hash provided by PassMark (e.g., C:\Downloads\memtest86-usb.iso.sha256).
- Publisher/Source: If the image is signed or accompanied by a manifest, verify the publisher shows "PassMark Software" or the official PassMark domain.
- Integrity Log: Review a local log at C:\Logs\memtest86-usb_hash_check.txt to confirm the hash matched and the image is intact.
Red Flags: If memtest86-usb is found in unusual folders (Temp, AppData), lacks a hash/signature, or reboots into other installers, stop and verify against the official PassMark download page.
Why Is memtest86-usb Running on My PC?
MemTest86-usb starts when you boot from a USB drive containing the MemTest86 image. It operates outside your installed operating system to perform RAM diagnostics, making it useful for diagnosing hardware memory issues.
Reasons it's running:
- Booted from USB: The system is configured to boot from the MEMTest86-usb media, so RAM tests begin automatically during startup.
- Hardware Diagnostics Mode: MemTest86-usb is designed to diagnose RAM faults, memory controller issues, and related hardware problems independent of the OS.
- Memory Stress Testing: The tool runs various test patterns that stress memory subsystems to reveal intermittent faults not visible under normal operation.
- BIOS/UEFI POST Interaction: Power-on self-test steps may trigger the memory test sequence if a bootable USB is detected as the primary boot device.
- Automated Pass Cycles: MemTest86-usb performs multiple passes and can loop until you manually stop it, especially during thorough validation.
Can I Disable or Remove memtest86-usb?
Yes, you can stop using memtest86-usb. It does not install software on your OS; to stop, remove the USB and reboot, or disable USB boot in BIOS/UEFI to prevent automatic startup.
How to Stop memtest86-usb
- Exit Test: Press Esc to exit tests and return to the boot menu or OS loader.
- Remove USB: Physically eject the MEMTest86-usb USB drive.
- Change Boot Order: Enter BIOS/UEFI setup and set the main hard drive as the first boot option.
- Power Cycle: Restart the computer to boot normally from the primary drive.
- Disable USB Boot (Optional): In BIOS/UEFI, disable USB boot to prevent automatic MEMTest86-usb startup on next power cycle.
How to Uninstall memtest86-usb
- ✔ Because memtest86-usb runs from a USB stick and does not install software, there is nothing to uninstall on the PC.
- ✔ If you no longer want to use MEMTest86-usb, simply remove the USB drive and reuse or reformat it as needed.
- ✔ If you want to reclaim the USB for other tasks, format the drive after backing up any data.
Common Problems: RAM Diagnostics with MemTest86-usb
If memtest86-usb is behaving unexpectedly or reporting errors, try these common scenarios and fixes.
Common Causes & Solutions
- USB not bootable on the target machine: Re-create the bootable MEMTest86-usb on a different USB drive using the official tool and ensure USB boot is enabled in BIOS/UEFI.
- Test runs extremely long or stalls: Ensure you allow multiple passes; reduce test complexity if needed, and verify RAM sticks are properly seated.
- Reported memory errors on all tests: Reseat RAM modules, test modules individually in different slots, and try known-good RAM to isolate faulty DIMMs.
- USB drive not detected after a reboot: Try another USB port (prefer USB 2.0/3.0 dedicated port), or reformat the USB drive to FAT32 and recreate the image.
- Boot failure on newer systems with UEFI: Use the UEFI-compatible image and ensure secure boot is disabled or compatible; select the MEMTest86-usb entry from the boot menu.
- Inconsistent test results across re-runs: Test in different RAM configurations and verify with a second test pass to confirm consistency; consider testing one module at a time.
Quick Fixes:
1. Re-create MEMTest86-usb on a fresh USB drive using the official download tool.
2. Ensure BIOS/UEFI is set to boot from USB first, then hard drive.
3. Run a single pass initially to confirm the test starts reliably.
4. If errors appear, reseat RAM modules and test one stick at a time.
5. Check for firmware updates for the motherboard that may affect memory detection.
Frequently Asked Questions
Is memtest86-usb safe to run?
Yes. MemTest86-usb is safe when downloaded from the official site and used as intended. It runs outside your OS and does not modify your data.
How long does memtest86-usb take to complete?
Duration depends on RAM size and test depth. A full multi-pass test on typical systems can take several hours; start with a single pass to gauge speed.
Will memtest86-usb erase my data?
No. MemTest86-usb only reads memory and reports errors. It does not write data to disk or alter user files.
Can memtest86-usb run on Windows or macOS?
No. MemTest86-usb runs from a bootable USB and operates outside any installed operating system.
What do RAM error messages mean?
MemTest86-usb reports failing addresses and patterns. Re-seat RAM, test modules individually, and replace defective DIMMs if errors persist.
Should I run all passes to trust the result?
Starting with several passes is recommended if issues are suspected. If errors recur consistently, replace the faulty RAM modules and re-test.