How to Run System Diagnostics on Windows 11 (Which Test for Which Symptom)

When a Windows 11 PC restarts on its own, freezes or boots slowly, the hard part is knowing which part to blame, and there is no single “diagnose everything” button. Reliability Monitor and Event Viewer show what already failed, the System Diagnostics report gives a one-minute snapshot, DISM and SFC repair Windows files, CHKDSK covers the drive, Windows Memory Diagnostic tests RAM, and the PC maker’s tool tests hardware outside Windows. Find your symptom below.

Which check to run for your symptom

Start with the row that matches what you are seeing. Most of these tools have their own section further down.

Symptom	Run this first	Then	Restart needed?	Admin rights?
Random restarts or blue screens	Reliability Monitor, then Event Viewer	Windows Memory Diagnostic	Yes, for the memory test	No for reading logs
Freezes, especially while opening files	System Diagnostics report	CHKDSK, drive health page	Only if CHKDSK repairs the system drive	Yes for CHKDSK
Windows features broken, Settings or Store errors	DISM, then SFC	Reliability Monitor to confirm the errors stop	Recommended after SFC repairs	Yes
Slow all the time	Task Manager (Ctrl + Shift + Esc), Performance tab	System Diagnostics report	No	No
Laptop battery drains fast or sleep misbehaves	powercfg /batteryreport	powercfg /energy	No	Yes for /energy
A device, display or sound problem	Device Manager	dxdiag, Get Help troubleshooter	No	Sometimes for driver changes
Everything above looks fine but the PC still fails	PC maker’s hardware diagnostics	Warranty or repair	Yes, runs before Windows loads	No

All of these are built into current versions of Windows 11. Before any repair tool, back up anything you cannot afford to lose and create a restore point (search Start for Create a restore point).

Read what already happened: Reliability Monitor and Event Viewer

Before you run a test, look at the records Windows already keeps. Yesterday’s crash is logged with a time, a source and often an error code, which points you to the right test faster than guessing.

Reliability Monitor

1. Select Start, type reliability, and open View reliability history. (You can also press Windows + R, type perfmon /rel, and press Enter.)
2. Read the chart. Each day gets a stability score, and the icons under the line mark application failures, Windows failures, warnings and informational events such as updates and installs.
3. Select a day with a red critical icon and read the list at the bottom. View technical details shows the faulting program or module and the error code.
4. Look at what happened just before the failures began. A driver update or new program on the day the crashes started is your first suspect.

Example: a laptop starts rebooting at random, and Reliability Monitor shows a graphics driver update installed that same morning. That is a software lead to chase before testing any hardware.

Event Viewer

Event Viewer holds the full logs that Reliability Monitor summarizes. Press Windows + R, type eventvwr.msc, and press Enter, then expand Windows Logs and select System. Use Filter Current Log in the right pane and tick Critical and Error to hide the routine entries. Two sources matter most for hardware questions: Kernel-Power event 41 means the PC lost power or hung without a clean shutdown, and disk or storahci errors point at the drive or its cable. The guide on opening Windows Event Viewer covers the other ways in. For blue screens specifically, the blue screen log in Windows 11 explains where the minidump files are and how to read the stop code.

Get the full System Diagnostics report from Performance Monitor

Performance Monitor can run a built-in data collector set that checks hardware, drivers, services and basic performance for about a minute, then writes a report with any warnings at the top.

1. Press Windows + R, type perfmon /report, and press Enter. If the report will not start, right-click Start, choose Terminal (Admin), and run the same command from there, because collecting some counters needs administrator rights.
2. Leave the PC alone while the status reads “Collecting data for 60 seconds”. Running programs during the collection skews the CPU and disk numbers.
3. Read the Warnings area under Diagnostic Results first. Each warning names the symptom, the likely cause and a suggested resolution. A red icon is an error, a yellow one a warning, and a green check means that check passed.
4. Expand Basic System Checks. Five groups (OS checks, disk checks, Security Center, system service and hardware device and driver checks) show a pass or fail for each test.
5. Expand Resource Overview for CPU, network, disk and memory use during the collection, and Hardware Configuration, Disk, Memory and CPU for details.

To reopen a report later, open Performance Monitor (perfmon) and expand Reports > System > System Diagnostics. Each run is kept with a date stamp, so you can compare a bad day with a good one.

Repair Windows files with DISM and SFC

If Reliability Monitor shows Windows components failing, or Settings, Start or the Store misbehave, check the Windows files themselves. Microsoft’s System File Checker instructions say to run DISM first, because DISM repairs the Windows image that SFC pulls replacement files from. Running SFC alone against a damaged image can report that it could not fix everything.

Warning: both tools change system files. Save your work and keep the window open until each command reports 100 percent.

1. Right-click Start and choose Terminal (Admin). Select Yes at the prompt.
2. Run DISM /Online /Cleanup-Image /RestoreHealth. It can sit at a percentage for several minutes; that is normal. DISM downloads replacement files through Windows Update, so the PC needs an internet connection.
3. When DISM finishes, run sfc /scannow and wait for the verification to reach 100 percent.
4. Read the final line against the table below, then restart.

SFC message	Meaning	Next step
Windows Resource Protection did not find any integrity violations	No damaged files	The problem is elsewhere; move on to the drive or memory tests
Windows Resource Protection could not perform the requested operation	SFC could not run fully	Run it again from Safe Mode, and check that the PendingRenames and PendingDeletes folders exist under %WinDir%\WinSxS\Temp
Windows Resource Protection found corrupt files and successfully repaired them	Fixed	Restart and watch whether the symptom returns
Windows Resource Protection found corrupt files but was unable to fix some of them	Partial repair	Run DISM again, then SFC again; read the log below for the file names

SFC writes everything it checked to %windir%\Logs\CBS\CBS.log. To pull out only the SFC lines, run findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt" and open the text file on the desktop. If Windows Update itself is broken, DISM can take a known-good source instead: mount a Windows 11 ISO of the same version and run DISM /Online /Cleanup-Image /RestoreHealth /Source:Wim:D:\sources\install.wim:1 /LimitAccess, replacing D: with the mounted drive letter and 1 with the index of your edition (list them with DISM /Get-ImageInfo /ImageFile:D:\sources\install.wim). A WIM source needs the Wim: prefix and an index, as Microsoft’s page on configuring a Windows repair source explains, and /LimitAccess stops DISM from trying Windows Update. Two quicker DISM options exist too: /CheckHealth only reports whether the image is healthy, repairable or non-repairable, and /ScanHealth takes a few minutes to scan without repairing, as described on Microsoft’s repair a Windows image page.

Check the drive and file system

Freezes while saving or opening files, programs that hang on launch and a boot that stalls on the spinning dots often come from the drive. Two different things can be wrong: the file system (fixable by CHKDSK) or the hardware itself (not fixable by any software).

Drive health in Settings

1. Open Settings > System > Storage.
2. Select Advanced storage settings > Disks & volumes.
3. Select the drive and choose Properties.
4. Under Drive health, read Estimated remaining life, Available spare and Temperature.

Windows shows this health data for NVMe SSDs only. A SATA SSD or a spinning hard drive shows no health section at all, so for those use the drive maker’s own utility, which reads the same SMART data. Microsoft’s page on critical warnings for a storage device lists the three warnings Windows can raise (“Spare capacity is low”, “Reliability is degraded” and “Drive is set to read-only”), and the advice for all three is the same: back up your data now.

CHKDSK

In Terminal (Admin), chkdsk C: with no switches runs a read-only check and changes nothing, so it is safe to try first. The switches that matter, from Microsoft’s chkdsk reference:

• /scan runs an online scan of an NTFS volume while you keep working, and queues anything it finds for a later fix.
• /f fixes file-system errors. It needs the volume locked, so on your system drive it offers to run at the next restart; on an external or data drive with nothing open it runs right away.
• /r looks for bad sectors and recovers readable data from them. It includes /f and can take hours on a large drive.
• /spotfix fixes only the problems queued by an earlier /scan, which is much faster than a full /f.

The exit code tells you what happened: 0 means no errors, 1 means errors were found and fixed, 2 means cleanup was done or skipped because /f was missing, and 3 means the disk could not be checked or the errors could not be fixed. Keep one thing in mind: CHKDSK repairs the index of where files live; it cannot repair a drive that is physically failing, and a drive that produces new errors every run is telling you to replace it. The CHKDSK guide for external drives in Windows 10 and 11 covers USB disks, which lock differently.

For a one-line status of every drive, run Get-PhysicalDisk | Select FriendlyName, HealthStatus, OperationalStatus in PowerShell. Anything other than Healthy and OK deserves a backup first and a maker’s test second.

Test the memory with Windows Memory Diagnostic

Blue screens with different stop codes each time, programs that crash with no pattern and file corruption that appears out of nowhere are classic signs of bad RAM. The built-in test needs a restart, so close everything first.

1. Save your work and close your programs.
2. Press Windows + R, type mdsched.exe, and press Enter.
3. Choose Restart now and check for problems (recommended), or Check for problems the next time I start my computer if you need to finish something first.

4. The PC restarts into a blue text screen and runs two passes of the standard test. Expect somewhere between ten minutes and well over an hour, depending on how much RAM is installed. Pressing F1 during the test opens options for the Basic, Standard or Extended mix and the number of passes; the Extended mix is far more thorough and far slower.
5. After the test, the PC boots into Windows normally. A notification with the result may appear after you sign in, but it is easy to miss.
6. To read the result reliably, open Event Viewer, go to Windows Logs > System, choose Filter Current Log, and pick MemoryDiagnostics-Results in the event sources list. The entry reads either that no errors were detected or that hardware problems were found.

If errors are found and the PC has more than one memory module, the usual next step is the maker’s test or testing one module at a time, because Windows reports that memory failed but not which stick.

Check devices, graphics and system details

Device Manager

Right-click Start and choose Device Manager. A device with a yellow warning triangle has a driver or resource problem; double-click it and read the Device status box on the General tab, which gives a short explanation and an error code you can search for. A device marked with a down arrow is simply disabled. The guide to opening Device Manager in Windows 11 lists every route in, including the one that works when Start itself is broken. For display or sound problems, dxdiag (Save All Information) and msinfo32 (File > Export) each write a text report you can send to a support person.

Troubleshooters

Go to Settings > System > Troubleshoot > Other troubleshooters for the audio, network, printer, Bluetooth and Windows Update troubleshooters. In Windows 11 most of these open in the Get Help app, which walks through the checks and offers to apply fixes. These troubleshooters repair settings, services and drivers; they do not test hardware, so a failing fan or a bad memory module will pass them.

Laptop battery and power reports

Two commands documented on Microsoft’s powercfg reference cover the most common laptop complaints.

1. Open Terminal (right-click Start > Terminal) and run powercfg /batteryreport. The command prints the path where it saved the HTML file; read that line rather than guessing, because the report lands in whatever folder the terminal is currently in. To pick a location, add /output "C:\Users\<name>\Desktop\battery.html"; to cover a longer history, add /duration 30 for 30 days.
2. Open the file in a browser and compare Design capacity with Full charge capacity under Installed batteries. A full charge capacity well below the design figure means the battery has worn; the Battery capacity history table shows how quickly it is declining. Some loss is normal with age and charge cycles; a fast decline over a few months, or a sudden drop, is what justifies a replacement.
3. For sleep, wake and drain problems, run powercfg /energy from Terminal (Admin) and leave the PC idle. It observes for 60 seconds by default and then writes an HTML report of errors and warnings, such as a device blocking sleep or a power policy set to maximum performance.

On a laptop that uses modern standby, powercfg /sleepstudy writes a report on sleep quality over the last three days to the current folder.

Run the PC maker’s own hardware tests

Every tool above runs inside Windows, so a flaky driver can muddy the result. The diagnostics built into most branded PCs run before Windows loads and test the processor, memory, storage, fans, battery and display directly. Use them when the Windows tools pass but the PC still fails, or when Windows will not boot.

• Dell: SupportAssist inside Windows, or the pre-boot diagnostics from the startup menu (often F12).
• HP: HP PC Hardware Diagnostics as an app, or the pre-boot version (often Esc or F2 at startup).
• Lenovo: Lenovo Vantage’s hardware scan, or diagnostics from the boot menu.

Startup keys vary by model, so check the maker’s support page. Write down any error code the test produces; warranty claims are keyed to those codes. Third-party stress tools exist too, but a maker’s test is the one a support line will ask for.

What the results point to and what to do when a test fails

No single result proves a diagnosis, but the patterns below are the common ones. Treat them as a starting point, not a verdict.

Finding	Often points to	Sensible next step
Blue screens with varied stop codes; Memory Diagnostic reports errors	RAM or memory slot	Maker’s memory test, then test modules one at a time
Freezes while reading files; disk errors in Event Viewer; CHKDSK finds new errors each run	Failing drive or cable	Back up today, run the drive maker’s utility, replace the drive
Kernel-Power 41 with no stop code; shutdowns under load	Power supply, overheating or a loose connection	Clean vents, check temperatures, maker’s thermal and PSU tests
SFC or DISM repairs files; crashes stop afterwards	Software corruption	Keep Windows updated; watch Reliability Monitor for a repeat
Crashes started on the day a driver or program was installed	That driver or program	Roll back the driver or uninstall, then retest
Everything passes; the problem persists	Intermittent hardware fault	Maker’s extended tests, then warranty or repair

When a test fails, resist the urge to reinstall Windows straight away; a clean install does nothing for failing memory or a dying drive. Instead, note the exact error code, back up your files, check Reliability Monitor for a matching install date, run the failing test a second time to rule out a one-off, and if the PC is under warranty, hand the maker the code. If the drive is the suspect, replace it before running anything else.

Windows 10 and work PCs

Every tool named here also exists in Windows 10, though the Storage health page sits in a different place there and some troubleshooters still run inside Settings rather than Get Help. The separate guide on running diagnostics on Windows 10 follows that layout. Microsoft ended Windows 10 support on October 14, 2025, so a Windows 10 PC without Extended Security Updates no longer gets security fixes; if a diagnostic pass turns up nothing wrong with the hardware, moving an eligible PC to Windows 11 is the sensible next job.

On a work or school PC, expect limits. Terminal (Admin), DISM, SFC and CHKDSK repairs all need an administrator account, which many organizations withhold, and Group Policy can hide the Troubleshoot page or block Performance Monitor data collection. The read-only tools (Reliability Monitor, Event Viewer, Task Manager, dxdiag, msinfo32 and the battery report) normally still work and give the help desk exactly what it needs, so run those and send the exports along with your ticket.

Once you know which part is at fault, the fix is usually short: a driver rollback, a file repair, a new drive or a warranty claim. Keep the exported reports; they tell the next person exactly what was tested and when.