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1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsWindows Memory Diagnostic is built into Windows 10 and Windows 11. Run mdsched.exe, choose whether to restart now or at the next boot, and let the computer test memory before Windows loads. Afterward, check the notification or Event Viewer for the result. A detected error is significant; a clean run means only that this test did not detect an error.
What Windows Memory Diagnostic does
Windows Memory Diagnostic is a built-in Windows utility that checks system memory in a pre-boot environment. It restarts the computer, runs selected memory tests before the normal Windows desktop loads, and restarts again when the test finishes. No separate download is required. Microsoft describes the utility and its test options in its Windows troubleshooting guidance.
A memory error can come from a RAM module, but the test does not necessarily identify the failed part. The memory subsystem also includes the motherboard slots, CPU memory controller, firmware, and memory settings. Crashes that appear to involve memory can also stem from drivers, storage, overheating, or other software and hardware problems; Microsoft lists hardware, drivers, and software among possible causes of stop-code errors in its unexpected restart and stop-code guidance.
Before starting the test
- Save open documents and close applications. Choosing an immediate test restarts the computer.
- Schedule the test for downtime if the computer is running a long task or is needed for work.
- Connect a laptop to AC power or make sure its battery is sufficiently charged.
- You normally do not need to disable BitLocker for this test. If you later change firmware or boot settings, have your recovery key available in case Windows asks for it.
How to start Windows Memory Diagnostic
Use Start search
- Open Start and search for Windows Memory Diagnostic.
- Open the matching Windows tool. Microsoft also recommends searching for Memory and selecting the diagnostic in its blue-screen troubleshooting instructions.
Use the Run dialog
- Press Windows key + R.
- Type
mdsched.exe, then press Enter or select OK. - Approve the User Account Control prompt if one appears.
Choose when the test should run
The utility offers two choices:
- Restart now and check for problems: Starts the test immediately after restarting. Choose this when your work is saved and the computer can be unavailable for the duration.
- Check for problems the next time I start my computer: Schedules the test for the next reboot; it does not begin testing immediately.
After a restart, the diagnostic screen appears and the test runs automatically. When it finishes, the PC restarts and returns to Windows. The test may seem inactive for a while, especially in Extended mode or on a system with a large amount of RAM; there is no universal runtime because duration depends on the system and test selection. Avoid interrupting it unless the computer is clearly unresponsive.
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Choose Basic, Standard, or Extended
The default test mix is Standard, a sensible first check. Basic is shorter and less comprehensive; Extended takes longer and runs a more thorough test mix, making it useful when problems are intermittent or a Standard run did not find an error.
- When the blue diagnostic screen appears, press F1.
- Under Test Mix, use the arrow keys to select Basic, Standard, or Extended.
- Press F10 to apply the selected settings.
Microsoft documents the F1 and F10 controls and changing the test mix in its Windows Memory Diagnostic instructions. A longer or more thorough run is not a guarantee that every possible fault will be found.
How to find the result
Windows may show a result notification after you sign in. If it does not appear or you dismissed it, check Event Viewer:
- Right-click Start and select Event Viewer.
- Open Windows Logs > System.
- Search the log for the source
MemoryDiagnostics-Resultsand open the event created after the latest test.
Microsoft also documents an alternate location under Applications and Services Logs > Microsoft > Windows > MemoryDiagnostics-Results > Debug. Navigation labels may vary, so searching the System log for the event source is often the simplest route. Microsoft says Event ID 2001 indicates that no memory errors were detected; read the event message and note which test you ran rather than treating the ID alone as a complete diagnosis. See Microsoft’s result and Event Viewer guidance.
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What the result means
No memory errors were detected
This means the selected run did not find an error. It does not certify every memory cell, slot, memory profile, or workload as stable. Intermittent faults may depend on temperature, load, or settings such as XMP or EXPO, and a clean result does not rule out a driver or storage problem.
Hardware problems were detected
Take this seriously, but do not assume the message proves a particular RAM stick is defective. Possible causes include a poorly seated or incompatible module, a faulty slot, unstable timings or voltage, an overclocking profile, firmware compatibility, or a motherboard or CPU memory-controller issue.
No result appears, or only a scheduling event is visible
Confirm that the computer actually restarted into the diagnostic screen, then search Windows Logs > System for MemoryDiagnostics-Results and inspect events from after that run. Microsoft Community guidance also points users to this source in the System log: Windows Memory Diagnostic result guidance. If the test did not complete or no result is recorded after a retry, use a bootable tester or the computer maker’s diagnostics.
What to do when errors are detected
- Shut down fully and disconnect power as appropriate for the computer. Follow its service manual before opening it.
- Reseat the modules, then test one module at a time in the single-DIMM slot recommended by the motherboard or computer manual.
- Test each module in the same known-good slot. If a module fails there while another passes, the module is a stronger suspect; if failures follow a slot, investigate the slot or board.
- Return firmware memory settings to defaults and retest before enabling XMP, EXPO, manual timings, or other overclocking.
- If modules pass alone but fail together, check compatibility, timings, voltage, recommended slots, and the system’s supported memory configuration.
If errors persist at default settings, use warranty or manufacturer service channels and replace a component only after isolating it as far as practical. Software cannot reliably repair defective RAM; excluding a bad address range is not a normal consumer fix.
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If the test passes but crashes continue
- Run the Extended test mix.
- Disable XMP, EXPO, undervolting, and other memory or CPU overclocks temporarily, then retest. If the system is stable at defaults but not with a performance profile, the profile or its settings may be unstable even if the modules are not physically defective.
- If the issue began after a RAM upgrade, reseat the new memory, check the recommended slots and compatibility information, and compare with the previous configuration if available.
- Install BIOS/UEFI firmware and chipset updates only from the system or motherboard manufacturer and follow its instructions.
- If instability remains, test modules individually and consider a bootable memory tester. Also investigate drivers, storage, temperature, and crash-dump clues rather than assuming every stop code containing “memory” proves bad RAM.
Windows Memory Diagnostic or MemTest86?
Windows Memory Diagnostic is convenient for a first check because it is already included and needs no USB drive. Its result reporting is basic, and a pass may not settle an intermittent problem. MemTest86 is a separate bootable utility from PassMark, not a Microsoft product. It can run without Windows loading, which is useful if Windows will not boot or if you want repeated testing. PassMark’s download page lists version 11.7 Build 1000 and says current images require UEFI; older BIOS-only machines need its older V4 release. Check the vendor’s page for current compatibility before preparing media.
PassMark describes MemTest86 as supporting multiple test algorithms, current memory technologies, USB and PXE boot, and ECC-related features in applicable editions. Those are vendor-described capabilities, not an independent comparison. Details are on the vendor’s MemTest86 feature page. MemTest86 is distinct from MemTest86+, a separate open-source project with a similar name. For ordinary home troubleshooting, start with Windows Memory Diagnostic and consider MemTest86’s free download if the built-in result is inconclusive or Windows cannot boot; Pro is not required for a basic check.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Special cases
Soldered laptop or compact-system memory
Some devices have RAM soldered to the board, so individual modules cannot be removed or replaced. Run the built-in test and, if needed, an independent test; reset firmware settings and contact the manufacturer or warranty service rather than opening a sealed or difficult-to-service device.
New or mixed memory kits
Modules that work individually may become unstable together because of different timings, chips, ranks, voltage requirements, slot loading, or system compatibility limits. Test at default settings first and check the system maker’s or motherboard maker’s supported configuration; a failure with a mixed kit does not establish that every module is defective.
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ECC memory
Error-correcting memory can correct or report some errors differently from ordinary consumer memory. PassMark advertises ECC detection and, in applicable editions, error-injection features; capabilities depend on the hardware and edition, so consult its ECC feature description rather than assuming every diagnostic installation offers them.
Windows will not boot
Windows Memory Diagnostic is easiest to schedule from a working Windows session. If Windows cannot start, use Windows Recovery Environment if available, remove recently installed RAM if that is safe and practical, or create a bootable memory-test USB on another computer. Follow the device maker’s service instructions and use the minimum hardware configuration it recommends.
The diagnostic appears stuck or keeps restarting
A long run is not necessarily frozen, but repeated restarts or a clearly unresponsive test can point to severe memory instability, firmware trouble, an overclock, a module or slot fault, or a motherboard or CPU issue. After allowing reasonable time for the selected test, power down only if the system is clearly unresponsive; then return firmware settings to defaults and test one module at a time, or try another diagnostic.
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