How to Run System Diagnostics on Windows 11

To run a full system diagnostics check on Windows 11, open Command Prompt as administrator, type perfmon /report, and press Enter. Windows collects data for about a minute, then opens a System Diagnostics report that lists any warnings about your hardware, software and performance. For a specific problem, use the matching built-in tool: DISM and SFC for Windows files, Windows Memory Diagnostic for RAM, and Device Manager or a troubleshooter for individual devices.

These steps apply to Windows 11 (24H2 and 25H2) as of October 2026. The same tools exist in Windows 10. None of them need extra software, and all except the file repair commands only read information.

Pick the Right Tool for Your Symptom

Windows 11 doesn’t have one button that tests everything. Start with the symptom you’re seeing:

• You don’t know what’s wrong, or the PC just feels off: run the System Diagnostics report first.
• Error messages, freezing, or Windows features that stopped working: check system files with DISM and SFC.
• Blue screens, random restarts, or crashes in many different apps: test your memory.
• Slow file opening, read errors, or clicking from a hard drive: check drive health and back up first.
• One device doesn’t work (sound, Wi-Fi, camera, printer): check Device Manager and run that device’s troubleshooter.

If you aren’t sure, work down this page in order.

Run a System Diagnostics Report

This is the closest thing Windows has to a whole-PC health check. Microsoft’s perfmon command reference says the /report option starts the System Diagnostics data collector set and displays the results.

1. Click Start, type cmd, then right-click Command Prompt and select Run as administrator. Click Yes at the User Account Control prompt. Our guide to opening Command Prompt in Windows 11 shows other ways in.
2. Type perfmon /report and press Enter. A Resource and Performance Monitor window opens and shows that it’s collecting data.
3. Wait about 60 seconds. Keep using the PC normally if the problem only appears during certain tasks.
4. Read the report when it appears. The Diagnostic Results section at the top lists Warnings first, each with a symptom, cause and suggested fix, followed by Basic System Checks with pass or fail results.

A warning tells you where to look next. For example, a disk or driver warning points you to the drive and Device Manager sections below. If the report shows no warnings and the basic checks pass, Windows didn’t find a configuration problem, but a failing part can still pass this report, so use the specific tests below for the symptom you have.

Check and Repair Windows System Files

Use DISM and System File Checker (SFC) when Windows shows errors, freezes, or has features that stopped working. DISM repairs the Windows image that SFC uses as its source, so run it first. These steps follow Microsoft’s System File Checker guide.

1. Open Command Prompt as administrator, as in the previous section.
2. Type DISM.exe /Online /Cleanup-image /Restorehealth and press Enter. DISM downloads clean copies of damaged files from Windows Update, so stay connected to the internet. It can take 10 minutes or more and may pause at 20% or 62% for a while.
3. When DISM says the operation completed, type sfc /scannow and press Enter.
4. Leave the window open until the verification reaches 100%, then read the final message.

What the SFC message means:

• Windows Resource Protection did not find any integrity violations. Your protected system files are fine. Move on to the next test for your symptom.
• Windows Resource Protection found corrupt files and successfully repaired them. Restart the PC and check whether the problem is gone.
• Windows Resource Protection found corrupt files but was unable to fix some of them. Run DISM and SFC once more and restart. If the message returns, the details are in C:\Windows\Logs\CBS\CBS.log, and Microsoft’s guide explains how to read it.
• Windows Resource Protection could not perform the requested operation. Start the PC in Safe Mode and run sfc /scannow again.

Never replace Windows files with DLL downloads from websites. That can add malware and rarely fixes the cause.

Test Your Memory (RAM)

Faulty RAM causes blue screens, random restarts and crashes in unrelated apps. Windows Memory Diagnostic tests it outside Windows, so you need to restart.

1. Save your work and close your apps.
2. Press Windows key + R, type mdsched, and click OK.
3. Click Restart now and check for problems (recommended). If you’d rather test later, choose Check for problems the next time I start my computer.

4. The PC restarts into a blue Windows Memory Diagnostics Tool screen and runs two passes. This usually takes 10 to 20 minutes, longer with a lot of RAM. Don’t turn the PC off.
5. Windows restarts on its own and shows the result in a notification a few minutes after you sign in.

If you missed the notification, check Event Viewer:

1. Right-click Start and select Event Viewer.
2. Expand Windows Logs and select System.
3. In the Actions pane on the right, click Filter Current Log.
4. Open the Event sources drop-down, check MemoryDiagnostics-Results, and click OK.
5. Open the newest entry and make sure its date matches your test. The General tab says whether any errors were detected.

If the test reports hardware errors, the RAM or the slot is likely faulty. On a desktop, you can test one memory stick at a time to find the bad one. On a laptop, especially one with soldered memory, contact the manufacturer.

Check Drive Health

Back up important files first if a drive is making noise, showing read errors, or acting oddly.

NVMe SSDs: open Settings > System > Storage > Advanced storage settings > Disks & volumes, select the drive, and click Properties. The Drive health section shows estimated remaining life, available spare and temperature. Microsoft’s storage warning guide explains that Windows monitors NVMe SSDs here but not SATA SSDs or hard drives.

SATA SSDs and hard drives: use the drive maker’s free diagnostic app, such as Samsung Magician, Crucial Storage Executive, WD Dashboard or Seagate SeaTools, and run its short test.

File system errors: run CHKDSK to check and fix the file system on a drive. CHKDSK checks how data is organized, not whether the hardware is wearing out, so a clean CHKDSK result doesn’t mean the drive is healthy.

If Windows shows a critical warning for a drive, copy your files off it before doing anything else, then contact the manufacturer. Don’t keep running repair commands on a failing drive.

Check Devices in Device Manager

A yellow warning icon next to a device in Device Manager means Windows found a problem with it.

1. Right-click Start and select Device Manager. See how to open Device Manager for other routes.
2. Look for a category that has expanded automatically or shows a yellow triangle, and expand it.
3. Right-click the device with the warning and select Properties.
4. Read the Device status box on the General tab. It describes the problem and usually shows an error code, such as Code 10 or Code 43.

Look up the code in Microsoft’s Device Manager error codes list for its fix. Most come down to restarting, updating the driver, or uninstalling the device and letting Windows reinstall it.

Run a Troubleshooter

Windows 11 troubleshooters now run in the Get Help app. Microsoft’s list of Windows troubleshooters includes audio, Bluetooth, camera, network and internet, printer, program compatibility, video playback and Windows Update.

1. Click Start, type the troubleshooter’s name, such as audio troubleshooter, and open the result. You can also open Get Help and search for the problem.
2. Follow the prompts. Get Help asks a few questions, runs its checks, and either applies a fix or tells you what it found.

Our guide on how to run a troubleshooter in Windows 11 covers each one in more detail.

Use Your PC Maker’s Hardware Diagnostics

Windows tools mostly check software and configuration. For a full hardware test of the CPU, battery, fans, display and drives, use the diagnostics from your computer’s manufacturer:

• Dell: SupportAssist, or the ePSA diagnostics by pressing F12 at startup and choosing Diagnostics.
• HP: HP PC Hardware Diagnostics Windows, or press F2 at startup for the UEFI version.
• Lenovo: Lenovo Vantage or Lenovo Diagnostics.
• Custom-built PCs: check the motherboard maker’s utilities, and the drive maker’s app for drive tests.

These tests run below Windows, so they can find hardware faults that Windows tools miss. Write down any error or validation code they show, because the manufacturer’s support team will ask for it.

Troubleshooting

“The requested operation requires elevation.” Close Command Prompt and reopen it with Run as administrator.

DISM fails with error 0x800f081f or can’t find source files. DISM couldn’t download repair files. Check your internet connection and that Windows Update works, then try again.

The memory test never shows a result. Check Event Viewer as described above. If there’s no MemoryDiagnostics-Results entry, the test didn’t finish, so run it again.

Every test passes, but the PC is still slow or crashing. Check the crash logs in Windows 11 for the error that appears when it fails. If the problem started after an update or a new app, System Restore can roll the system back to an earlier point.

Frequently Asked Questions

Does Windows 11 have a built-in diagnostic tool?

Yes, several. The System Diagnostics report (perfmon /report) gives an overview, and SFC, DISM, Windows Memory Diagnostic, Device Manager and the Get Help troubleshooters each check one part of the PC.

Will running diagnostics delete my files?

No. The report, memory test, Device Manager and troubleshooters only read information. DISM and SFC replace damaged Windows system files but don’t touch your personal files.

How long does a full diagnostic check take?

The System Diagnostics report takes about a minute. DISM and SFC together usually take 15 to 30 minutes, and the memory test takes 10 to 20 minutes or more, depending on how much RAM you have.

How do I test my computer’s hardware?

Use Windows Memory Diagnostic for RAM, the drive health page or the drive maker’s app for storage, and your PC maker’s hardware diagnostics for everything else. Our guide on how to check your system configuration in Windows 11 shows how to see which parts your PC has.