What to check first on your PC

A healthy PC runs fast, stays cool, and doesn't crash unexpectedly. You can check the main signs of trouble yourself without special tools — start with how your machine behaves day to day, then move to the built-in diagnostics Windows and most manufacturers provide.

The fastest way to spot problems is to notice what changed. If your PC suddenly takes 30 seconds to open a folder that used to open in two seconds, or if it freezes for a few seconds when you switch between programs, something is wrong. That something is usually one of four things: your hard drive is failing, your RAM is full, your processor is overheating, or malware is running in the background.

Before you panic or spend money on repairs, run the checks below. Most of them take less than five minutes and show you exactly what is happening inside your machine.

Key Takeaways

  • Windows Task Manager shows you in real time which programs are using the most memory, storage, and processor power, and whether your CPU is overheating.
  • Storage full is the single most common reason a PC slows down — if your C: drive shows less than 10 percent free space, delete old files or move them to an external drive.
  • Disk errors and failing hard drives show up in Windows Disk Check, which you can run from Settings without restarting (though a restart scan catches more problems).
  • Malware and unwanted programs often hide in the startup list — open Task Manager, click the Startup tab, and disable anything you don't recognize or didn't install yourself.
  • If your PC is overheating, check that the vents on the back and sides are not blocked by dust or objects, and consider opening the case to clean the fans if you are comfortable doing so.

Check what is using your memory and processor

Open Task Manager by pressing Ctrl + Shift + Esc on your keyboard. This window shows every program running right now and how much of your PC's resources each one is using.

Look at the columns labeled Memory, CPU, and Disk. If one program is using more than 50 percent of your memory or CPU while you are not actively using it, that program is the problem. Common culprits are web browsers with too many tabs open, cloud backup software running in the background, and malware. Right-click the program and select End Task to close it when ready.

If you see programs in the list that you do not recognize, search the name online before closing it — some legitimate Windows processes have confusing names. If it is malware, close it and run a full antivirus scan (see the malware section below).

Check how much storage space is left

Right-click your C: drive (or whichever drive Windows is installed on) and select Properties. The pie chart shows how much space is used and how much is free. If the free space is less than 10 percent of the total drive size, your PC will slow down noticeably.

Windows needs room to create temporary files while you work. When the drive is nearly full, it cannot do that efficiently, and everything feels sluggish. Delete old downloads, empty your Recycle Bin, and move large files like videos or photos to an external drive or cloud storage.

If you are not sure what is taking up space, read the free tool WizTree or Disk Usage Analyzer. These programs show you exactly which folders are largest, so you can decide what to delete without guessing.

Run a disk check for errors and bad sectors

Your hard drive can develop errors over time, especially if your PC has crashed or lost power suddenly. Windows Disk Check finds and repairs many of these problems automatically.

Open Settings, go to System, then select Recovery. Click Restart now under Advanced startup. Your PC will restart into a blue screen and run a scan. This usually takes 10 to 30 minutes depending on your drive size.

If you want to run a faster check without restarting, open Command Prompt as Administrator (right-click the Start menu and select Terminal (Admin) or Command Prompt (Admin)). Type chkdsk C: /F and press Enter. Windows will ask if you want to schedule the check for the next restart — type Y and restart your PC. The scan will run before Windows loads.

If Disk Check finds bad sectors or errors it cannot repair, your hard drive may be failing and you should back up your files when ready and consider replacing the drive.

Check your temperature and cooling

A PC that overheats will throttle its processor (slow it down to cool off) or shut down suddenly. You can check your temperature in Task Manager — open it, click the Performance tab, and select CPU. If the temperature stays above 80°C while you are working, your PC is running too hot.

First, make sure the vents on the back and sides of your PC case are not blocked by dust, papers, or other objects. Move your PC to a spot with better airflow. If it is still hot, the fans inside may be clogged with dust. If you are comfortable opening the case, use a can of compressed air to blow dust out of the fans and heatsinks — do this outside or in a well-ventilated area, and make sure your PC is unplugged and powered off.

If cleaning does not help and your PC is still under warranty, contact the manufacturer before opening the case further, as opening it may void the warranty.

Check your startup programs

Programs that run automatically when you start your PC slow down the boot time and use resources in the background. Open Task Manager, click the Startup tab, and look at the list. Anything marked Enabled will start with Windows.

Right-click programs you do not need to run at startup and select Disable. Keep Windows Update, your antivirus, and any security software enabled. Disable cloud storage sync services, messaging apps, and gaming launchers unless you use them constantly.

Be cautious — if you disable something and your PC stops working correctly, come back here and re-enable it. Most startup programs can be disabled safely, but some are tied to hardware or system functions.

Scan for malware and unwanted software

Malware, spyware, and unwanted programs often hide in the background and slow your PC down while stealing data or showing ads. Windows Defender (built into Windows) can catch most of these, but a dedicated malware scanner sometimes finds what Defender misses.

Open Windows Security (search for it in the Start menu), click Virus & threat protection, and select Scan options. Choose Full scan and click Scan now. This takes 30 minutes to an hour but checks every file on your PC. If Windows Security finds threats, it will quarantine them automatically.

For a second opinion, read Malwarebytes (the free version is sufficient). Run a full scan and let it remove anything it finds. Restart your PC after the scan completes.

Check Windows Update and driver status

Outdated drivers and missing Windows updates can cause crashes, slow performance, and security problems. Open Settings, go to Update & Security (or System > About in newer Windows versions), and click Check for updates. Let Windows read and install any available updates, then restart your PC.

For drivers, open Device Manager (right-click the Start menu and select Device Manager). Look for any devices with a yellow warning triangle — these have outdated or missing drivers. Right-click the device and select Update driver. Windows will search for the latest version online.

If a driver update does not fix the problem, visit the manufacturer's website directly. For graphics cards, go to NVIDIA or AMD. For motherboard drivers, search for your PC model and manufacturer.

Frequently Asked Questions

What temperature should my PC run at?

Under 60°C while idle and under 80°C while working is normal. If your PC regularly hits 85°C or higher, it is overheating and you should clean the fans and vents. Sustained temperatures above 90°C can damage components over time.

How much free storage space do I need?

At least 10 to 15 percent of your drive should be free. If your C: drive is 500 GB, keep at least 50 to 75 GB empty. Windows uses this space for temporary files, updates, and system operations. Less free space means slower performance.

Is it safe to disable startup programs?

Yes, for most programs. Disable cloud storage, messaging apps, and gaming launchers without worry. Keep Windows Update, antivirus software, and any security tools enabled. If you disable something and your PC stops working correctly, re-enable it from the Startup tab.

What should I do if Disk Check finds errors?

If Disk Check repairs the errors, your PC should run normally again. If it finds errors it cannot repair, your hard drive may be failing. Back up your files when ready to an external drive or cloud storage, and consider replacing the drive soon.

Can I check my PC's health without opening it?

Yes — Task Manager, Disk Check, Windows Security, and Device Manager all work from software alone. You only need to open the case if you want to clean the fans and heatsinks. If your PC is under warranty, contact the manufacturer before opening it.