Windows • UEFI • Secure‑Boot
MemTest86 — Test Your RAM Before Windows Starts
Boot from a USB and run MemTest86 outside the operating system. This stand‑alone test accesses nearly all memory and uses modern patterns to reveal the hardware faults behind BSODs, freezes, and silent file corruption.
* ECC visibility depends on your CPU, motherboard, and firmware support.
Quick Start
Download the Windows ZIP, run imageUSB.exe to create the USB, reboot to UEFI/BIOS, and boot from the USB device.
Practical Tips
Run multiple passes. If errors appear, test one module at a time to identify the failing DIMM or slot.
Integrity
Verify downloads (SHA‑256) before booting. Keep your USB ≥ 1 GB and safely eject after writing.
Why Choose MemTest86?
MemTest86 is a free, self-booting tool trusted globally to diagnose and surface RAM issues that standard diagnostics often miss. Powered by decades of refinement, EFI/BIOS support, security, logging, and automation, it’s the industry standard for memory validation.
Bootable & Stand-Alone
Runs outside your OS—boot from a USB (or network PXE), and test your entire memory space on x86 or ARM platforms.
Secure, Automated & Network-Ready
Secure Boot signed by Microsoft, complete logging to USB or network, full automation via config files, and PXE deployment make it enterprise-ready.
Powerful Reporting & ECC Monitoring
Create rich HTML reports, support multiple languages, blacklist bad memory addresses, and surface ECC errors directly on-screen.
Powerful Features of MemTest86
UEFI Boot & Hardware Access
MemTest86 boots directly from UEFI firmware, bypassing Windows. This ensures full low-level access to your memory hardware without interference from drivers or background apps.
- Secure Boot compatible
- Supports DDR4 & DDR5 RAM
- Detects faulty memory modules before OS loads
Advanced Test Algorithms
Unlike simple benchmarks, MemTest86 uses specialized memory patterns to expose subtle and rare memory errors that everyday use might miss.
- Moving inversions, random fill, block moves
- Row Hammer testing for modern DRAM vulnerabilities
- Stress patterns proven in real-world debugging
Detailed Reporting
MemTest86 generates clear, actionable reports to help you validate stability, troubleshoot system crashes, or document hardware faults for warranty claims.
- Readable HTML reports for users
- Machine-friendly JSON logs
- Error addresses & bit patterns included
ECC Memory Support*
If your system supports ECC (Error-Correcting Code) RAM, MemTest86 can detect and report ECC errors, giving advanced visibility into silent memory corruption.
- Logs both corrected & uncorrected errors
- Helps identify failing DIMMs early
- *Support depends on motherboard & CPU
Ease of Use
The included imageUSB tool makes creating a bootable USB drive simple. Even non-technical users can get MemTest86 running in just a few steps.
- One-click USB creation
- Bootable from most modern PCs
- No installation required
Trusted Worldwide
Used by PC enthusiasts, hardware reviewers, and IT professionals for over two decades. MemTest86 is the go-to tool for diagnosing RAM stability issues.
- Community-endorsed on forums & Reddit
- Regularly updated for new chipsets
- Free for personal & commercial use
Download MemTest86
Create a bootable USB, test RAM outside Windows, and save clear reports. Secure‑Boot compatible, UEFI‑first, with a legacy option for BIOS‑only systems.
Choose Your Download
Pick the Windows package for the quickest setup, or use the ISO images if you prefer your own writer.
System Requirements
- Modern PC with UEFI (latest build) or BIOS (legacy v4)
- USB flash drive ≥ 1 GB
- Windows 10/11 to create the boot USB (ZIP includes writer)
Verify Integrity
Always verify your download before booting:
Help & Troubleshooting
Frequently Asked Questions
Does MemTest86 require UEFI? What if my PC only has Legacy BIOS?
Current builds of MemTest86 boot on UEFI systems. If your machine is BIOS-only (CSM/Legacy), use the Legacy v4 release instead. Apple Silicon (M1/M2/M3) Macs aren’t supported.
Go to Older Versions for v4 CD/USB images, or use the main Download page for UEFI builds.
How do I create a bootable USB on Windows?
Download the Windows ZIP, extract it, then run imageUSB.exe from the folder.
- Select your USB drive (≥ 1 GB) and keep the included image pre-selected.
- Click Write. This erases the USB and makes it bootable.
- Safely eject when complete.
How do I create the USB on Linux or macOS?
Unzip the package and write the included memtest86-usb.img to your USB drive with Etcher or dd:
sudo dd if=memtest86-usb.img of=/dev/sdX bs=4M status=progress conv=fsync (replace sdX with your USB device)
On macOS you can also use Etcher (GUI). Eject the USB when done.
How do I boot from the USB? Which key opens the boot menu?
Insert the USB, restart, and open the one-time boot menu in firmware. Common keys: F12 (Dell/Lenovo/Gigabyte), F11 (MSI), F8 (ASUS), Esc (HP). Choose your USB under the “UEFI:” list (or legacy USB for v4).
How many passes should I run?
For most checks, about 4 passes is a practical target. For intermittent issues, let it run longer (overnight). Extremely long runs over days can surface “soft errors” from cosmic rays or electrical noise, so interpret those carefully.
MemTest86 found errors — what should I do?
- Isolate the fault: test each DIMM one-by-one and try different slots.
- Revert memory to default/JEDEC timings; remove XMP/EXPO overclocks.
- If your board allows, try a slight DRAM voltage increase within safe spec.
- Update BIOS/UEFI to the latest stable release.
- If a module keeps failing in multiple slots, replace/RMA the RAM.
Does MemTest86 support ECC memory and ECC error injection?
ECC visibility depends on your CPU, chipset, and firmware. MemTest86 Pro can perform ECC error injection on platforms that expose this capability in hardware/BIOS. On consumer platforms without ECC, those features aren’t available.
My USB shows the wrong size after testing — how do I restore it?
Open imageUSB.exe and use Reformat USB (or “Zero USB drive” then replug and format). This restores the full capacity after imaging.
Where can I get the Legacy BIOS (v4) images?
Use the Older Versions section of the Downloads page for v4 images (CD/USB/Floppy). Choose Windows or Linux/Mac, write the image to media, and boot via BIOS/CSM.