What is a BSOD?
A BSOD (Blue Screen of Death), officially a stop error or bug check, is the full-screen error Windows shows when it hits a problem it can't safely recover from. Windows halts, can write a memory dump to disk, and restarts. The screen shows a stop code such as IRQL_NOT_LESS_OR_EQUAL, and recent versions add a QR code that links to Microsoft's help.
Common causes
- Faulty or incompatible drivers, the most common cause, especially right after a driver or Windows update.
- Failing hardware: bad RAM, a failing storage drive, overheating, or a power supply that can't deliver stable power.
- Corrupted system files or a damaged boot configuration.
- Malware that tampers with the kernel or drivers.
- Unstable overclocks on the CPU, RAM or GPU.
Common stop codes
| Stop code | What it usually points to |
|---|---|
IRQL_NOT_LESS_OR_EQUAL (0x0000000A) | A driver touching memory it shouldn't; sometimes bad RAM |
PAGE_FAULT_IN_NONPAGED_AREA (0x00000050) | Bad RAM, a faulty driver or a corrupted file system |
SYSTEM_SERVICE_EXCEPTION (0x0000003B) | A driver or system service fault |
CRITICAL_PROCESS_DIED (0x000000EF) | A core Windows process stopped, often from corrupted system files |
INACCESSIBLE_BOOT_DEVICE (0x0000007B) | Windows can't reach the boot drive: a storage driver or SATA mode (AHCI/RAID) change, or a failing drive |
Troubleshooting a BSOD
- Write down the stop code and any file named on the screen, such as a
.sysdriver file. - Ask what changed: a new driver, update, app or piece of hardware. Roll back the driver, uninstall the update or remove the hardware.
- If Windows won't stay up, boot into Safe Mode or the Windows Recovery Environment and use System Restore or Startup Repair.
- Check Event Viewer (the System log) and Reliability Monitor for the crash and what led up to it.
- Test the hardware: Windows Memory Diagnostic for RAM, the drive's S.M.A.R.T. status, and temperatures.
- Repair system files with
sfc /scannowandDISM /Online /Cleanup-Image /RestoreHealth. - Scan for malware and remove any overclock.
For the CompTIA A+ exams
Both cores cover it: Core 1 (220-1201) lists proprietary crash screens such as the BSOD under hardware troubleshooting, and Core 2 (220-1202) covers it under Windows troubleshooting. When a question describes a blue screen right after a new driver or hardware install, the usual first step is to roll back or remove that change.