What IRQL_NOT_LESS_OR_EQUAL means
The "IRQL" is the priority level the processor was running at. This stop happens when kernel code, normally a driver, accesses memory that is not valid for the current priority level. It is one of the most common blue screens and points much more often to a driver or memory problem than to Windows itself.
Common causes
- A buggy or outdated driver; network, VPN and security-software filter drivers are frequent suspects
- Faulty RAM or memory settings that are not stable
- Newly added hardware, or a device with a failing connection
- Overclock or undervolt instability
How to fix IRQL_NOT_LESS_OR_EQUAL
Work through these in order and test after each one. Stopping as soon as the crashes stop tells you which change mattered.
- Note the file name on the blue screen. If the screen shows a line such as "What failed" followed by a .sys file, write it down. Searching that file name shows which driver it belongs to, which tells you what to update or remove. The named file is the code that crashed, which is not always the root cause.
- Undo the most recent change. If the blue screens began after a Windows update, a new driver or new software, remove that change first. Uninstall the update from Settings, Windows Update, Update history, or roll a driver back in Device Manager (right-click the device, Properties, Driver, Roll Back Driver). Network and VPN drivers are worth special attention for this code.
- Test the memory. Run Windows Memory Diagnostic (search for it in Start) for a quick check, then MemTest86 for several passes if the crashes continue. Any error points to a faulty stick or slot, or to memory settings the hardware cannot run reliably.
- Return the PC to stock settings. Reset the BIOS to defaults, then leave XMP or EXPO, CPU or GPU overclocks and undervolts (including per-core offsets such as Curve Optimizer) switched off while you test. If the crashes stop, re-enable one setting at a time to find the unstable one.
- Disconnect hardware you added recently. Unplug new USB devices, capture cards or add-in cards and run the PC for a few days. If the crashes stop, reconnect one device at a time and update or replace the driver of the one that brings them back.
If crashes continue with every optional device removed and memory tests clean, a failing motherboard component becomes more likely and a clean Windows installation is a useful test.
Not sure this is your code?
The stop code appears as text on the blue screen. If the PC restarted before you could read it, open Event Viewer, then Windows Logs, then System, and look for a BugCheck event with ID 1001. You can also search all stop codes.