Windows Memory Diagnostic Tool: 6 Proven Steps to Test RAM

Written by: Kymakers Support Team · Reviewed by: Kymakers Technical Team Last updated: July 2026 · Applies to: Windows 10, Windows 11 Difficulty: Beginner · Estimated time: 20–60 minutes

The Windows Memory Diagnostic Tool is a free built-in utility that tests your RAM for faults. To run it, press Windows + R, type mdsched.exe, press Enter, and choose Restart now and check for problems. The test runs before Windows loads and takes 15 to 30 minutes.

Faulty RAM causes symptoms that look like everything else — random blue screens, crashes with no pattern, freezes, corrupted files. That’s why testing memory is worth doing early rather than after weeks of chasing drivers. This guide covers running the Windows Memory Diagnostic Tool, finding results (which is less obvious than it should be), and what to do when it finds errors.

Why RAM problems are so confusing

Bad memory doesn’t fail predictably. A faulty stick may work fine for hours, then corrupt whatever happens to be in the bad region — which could be a system file, an app, or a driver. That’s why the resulting crashes look random and the stop codes keep changing. If you’re seeing different blue screen errors each time, memory is a prime suspect.

Table of Contents

1. Step 1: Run the Windows Memory Diagnostic Tool
2. Step 2: Choose the right test mode
3. Step 3: Find the results (they’re hidden)
4. Step 4: What to do if it reports errors
5. Step 5: Test one stick at a time
6. Step 6: When you need a more thorough test
7. Symptoms that point to RAM
8. FAQ

Step 1: Run the Windows Memory Diagnostic Tool

The test can’t run while Windows is using the memory, so it runs before Windows loads.

1. Press Windows + R, type mdsched.exe, and press Enter. (You can also search “Windows Memory Diagnostic” in the Start menu.)
2. Choose Restart now and check for problems (recommended) — or schedule it for the next restart if you have work open.
3. The PC restarts into a blue diagnostic screen and begins testing automatically.
4. Let it finish. The standard test takes 15 to 30 minutes depending on how much RAM you have.
5. Windows restarts on its own when done.

Don’t interrupt it. A partial test tells you nothing, and forcing a shutdown mid-test isn’t useful.

Step 2: Choose the Right Test Mode

By default the Windows Memory Diagnostic Tool runs its Standard test, which is fine for most people. But if you suspect memory and Standard comes back clean, run the Extended test.

While the test is running, press F1 to open options:

• Basic — fast, catches only obvious faults. Rarely worth it.
• Standard — the default. Good balance of coverage and time.
• Extended — significantly more thorough, and significantly slower (can run for hours). Use this when Standard passes but you still suspect RAM.

You can also change the pass count with the Tab key. More passes catch intermittent faults that a single pass misses — worth it for a stick that fails only occasionally.

Press F10 to apply and restart the test.

Step 3: Find the Windows Memory Diagnostic Tool Results

This trips people up constantly: the Windows Memory Diagnostic Tool often restarts into Windows without showing anything, and the notification disappears in seconds. The results are in Event Viewer.

1. Press Windows + R, type eventvwr.msc, press Enter.
2. Expand Windows Logs → System.
3. Click Find on the right, type MemoryDiagnostics-Results, and press Enter.
4. Open the matching event.

The description tells you plainly whether errors were detected. “The Windows Memory Diagnostic tested the computer’s memory and detected no errors” means your RAM passed. Anything reporting detected errors means a hardware fault.

Step 4: What to Do If It Reports Errors

If the Windows Memory Diagnostic Tool reports errors, that’s a hardware fault — no software fix exists. RAM can’t be repaired; it gets replaced.

Before buying anything, though, try the cheap checks:

• Reseat the modules. Power off, unplug, open the panel, remove each RAM stick and firmly re-insert it until the clips click. A poorly seated stick produces exactly these errors, and reseating costs nothing.
• Clean the contacts gently if there’s visible dust.
• Check for overclocking. If XMP/EXPO memory profiles are enabled in BIOS, disable them and retest. Unstable overclock settings cause errors on perfectly healthy RAM.

Retest with the Windows Memory Diagnostic Tool after each change. If errors persist with everything reseated and at stock settings, the module is faulty.

Step 5: Test One Stick at a Time

If your PC has multiple RAM sticks and the Windows Memory Diagnostic Tool found errors, you need to know which stick is bad — replacing both when one is fine wastes money.

1. Power down and remove all sticks except one.
2. Run the test with just that stick installed.
3. Repeat for each stick individually, noting results.

The stick that produces errors on its own is the faulty one. If every stick passes alone but the set fails together, suspect the motherboard slot or an incompatible pairing — try the working stick in each slot to identify a bad slot.

Most laptops (including Acer models with two SODIMM slots) allow this; check your model’s service manual for access.

Step 6: When You Need a More Thorough Test

The Windows Memory Diagnostic Tool is convenient but not exhaustive. It can pass memory that a deeper test would fail.

If you strongly suspect RAM — repeated crashes with changing stop codes, corruption that keeps returning — but the built-in tool passes, a dedicated memory tester running multiple passes over several hours will catch faults the standard test misses. Run it overnight; intermittent faults often only appear after hours of sustained testing.

Conversely, if the built-in tool does report errors, believe it. False positives are rare — a reported error almost always means a genuine hardware problem.

Symptoms That Point to RAM

Worth running the Windows Memory Diagnostic Tool if you’re seeing:

• Blue screens with changing stop codes — especially MEMORY_MANAGEMENT, PAGE_FAULT_IN_NONPAGED_AREA, or IRQL_NOT_LESS_OR_EQUAL.
• Random crashes with no pattern — no consistent trigger, no particular app.
• File corruption that keeps returning after repairs.
• Freezes during memory-heavy work — video editing, large spreadsheets, gaming.
• Failure to boot with beep codes from the motherboard.
• Crashes that survive a clean Windows install — the clearest sign the problem is hardware, not software.

If you’ve already run SFC and DISM and checked hard drive health with no answer, memory is the next thing to rule out. For Acer laptops specifically, our blue screen Acer guide covers the full diagnostic order.

FAQ About the Windows Memory Diagnostic Tool

How do I run the Windows Memory Diagnostic Tool? Press Windows + R, type mdsched.exe, press Enter, and choose “Restart now and check for problems.” The test runs before Windows loads and takes 15–30 minutes.

Where are the Windows Memory Diagnostic results? In Event Viewer. Open eventvwr.msc, go to Windows Logs → System, use Find, and search for MemoryDiagnostics-Results. The event description states whether errors were found.

How long does the memory test take? The Standard test typically takes 15–30 minutes. The Extended test is far more thorough and can run for several hours — use it when Standard passes but you still suspect RAM.

What do I do if it finds memory errors? Reseat the RAM modules, disable any XMP/overclock profile in BIOS, and retest. If errors persist, the module is faulty and needs replacing — RAM can’t be repaired.

Can the Windows Memory Diagnostic Tool fix RAM problems? No. It only tests and reports. Memory faults are hardware, so the fix is reseating a loose module, correcting overclock settings, or replacing the stick.

Is it safe to run the memory diagnostic? Yes. It only reads and writes to memory during the test and doesn’t touch your files. Just don’t interrupt it partway through.

The Windows Memory Diagnostic Tool is free and built into Windows, so ruling out RAM costs nothing but time. If your testing points to software rather than hardware and you end up doing a clean reinstall, Kymakers supplies genuine Windows 11 Pro and Windows 10 Pro keys with instant delivery and activation support.

Test the memory early. Read the results in Event Viewer. Reseat before you replace — and test one stick at a time before buying anything.

Official reference: Windows Memory Diagnostic — Microsoft Support