A bootloop is one of the most unnerving faults a PC can have. You press the power button, the fans spin up, the lights come on — and then, before you ever reach your desktop, the machine cuts and restarts. It does this again, and again, in an endless cycle. Nothing you click stops it because it never gets far enough to let you click anything. The good news is that bootloops follow predictable patterns, and once you know what to look for, most are fixable at home.
The single most useful thing you can do is work out when in the boot process the restart happens. That one observation splits every bootloop into two completely different problems with different fixes. If yours sometimes reaches Windows and sometimes does not, our guides on a PC that keeps restarting randomly and a PC randomly shutting down cover the overlapping symptoms in more detail.
First, classify the loop: hardware or Windows?
Before you touch anything, watch two or three full loops and answer one question: does the machine ever show the Windows logo or load your desktop before it restarts? Where the restart happens tells you which half of this article to read.
- Hardware or BIOS loop — the PC restarts at or before POST. You see the manufacturer logo or a black screen, fans may rev up and down, but Windows never starts loading. This points to power, cooling, seating, or BIOS settings.
- Windows loop — the PC reaches the Windows logo, maybe even the desktop, then crashes or restarts. You might see a spinning loader, a brief blue screen, or an "Automatic Repair" message that loops back to a restart. This points to a bad update, corrupt system files, or a failing drive.
Get this classification right and you save yourself hours. A hardware loop will not be fixed by reinstalling Windows, and a Windows loop will not be fixed by reseating your RAM.
Hardware loop: power is the first suspect
In Nigeria, the most common cause of a hardware bootloop is power — either inside the case or coming from the wall. A power supply unit (PSU) that is failing, undersized, or struggling with unstable mains cannot hold a steady voltage under load. The moment the system draws current to start, the voltage sags, the motherboard detects the fault, and it resets to protect itself. The result is a loop that often gets worse when the machine warms up or when the grid is dirty.
Check whether your mains is steady and whether the PSU is healthy. If the loop coincides with NEPA fluctuations, generator switchovers, or a tired unit, your power chain is the likely culprit. Our guides on how to tell if your PSU is failing and a PC that shuts down under load walk through the symptoms and tests in detail.
Hardware loop: cooling, seating, and CMOS
If power checks out, work through these in order. Most hardware loops are resolved by one of them, and none requires spare parts.
- Overheating shutdown — if the CPU cooler has come loose or was never seated properly, the processor hits its thermal limit within seconds and the board cuts power to protect it, then tries again. Power down, open the case, and confirm the cooler is firmly mounted with clean contact against the CPU. Reseat it if there is any wobble.
- RAM or GPU not seated — a memory stick or graphics card that has crept loose (common after moving the machine) can stop POST from completing. Power off, remove and firmly reseat each RAM stick until it clicks, and push the GPU fully back into its slot.
- A bad BIOS setting or failed overclock — if you recently changed a BIOS setting or pushed an overclock that the hardware cannot sustain, the board may loop trying to apply it. Clearing the CMOS resets the BIOS to safe defaults and fixes a surprising number of loops. Power off at the wall, then either move the CLR_CMOS jumper or remove the small silver battery on the motherboard for a minute before replacing it.
- A recent BIOS update gone wrong — a firmware update interrupted mid-flash, often by a power cut, can leave the board in a loop. Many boards have a recovery mode; check your motherboard manual for the procedure.
Windows loop: undo the last change
If the machine reaches Windows before it restarts, the hardware is probably fine and the problem is in the software. The classic version is the "Automatic Repair" loop, where Windows tries to repair itself, fails, and reboots straight back into the same screen.
The usual trigger is a recent change — a Windows update or a driver that did not install cleanly. To undo it, let the machine fail to boot two or three times and Windows should drop you into the recovery environment. From there:
- Choose Troubleshoot, then Advanced options, then Startup Settings, and restart into Safe Mode. Safe Mode loads only the essentials, so if a driver or update is the culprit you can usually reach the desktop.
- From Safe Mode, uninstall the most recent Windows update or roll back the driver you last changed. A graphics driver is a frequent offender.
- If you cannot reach Safe Mode, use System Restore from the recovery menu to roll the system back to a point before the loop started.
Windows loop: repair corrupt boot files
The other major cause of a Windows loop in Nigeria is corruption from a power cut mid-update. If NEPA dropped while Windows was writing files, the boot data or system files can be left half-written, and the machine loops because it cannot load a coherent system.
From the recovery environment, run Startup Repair first — it fixes many bootloader problems automatically. If the loop persists, open Command Prompt from the advanced options and run the SFC and DISM repair tools to scan and restore protected system files. If you are also seeing crash codes flash before each restart, our guide on decoding blue screen errors helps identify the failing component, and our walkthrough on a PC that posts but will not boot Windows covers bootloader repair step by step. If repairs keep failing and the drive makes odd noises or vanishes from the BIOS, a failing drive may be the root cause.
Frequently Asked Questions
How do I tell a hardware loop from a Windows loop? Watch when the restart happens. If it cuts before you ever see the Windows logo, it is a hardware or BIOS loop — check power, cooling, seating, and clear the CMOS. If it reaches the Windows logo or desktop first, it is a Windows loop — boot to recovery and undo the last update or repair the system files.
Will clearing the CMOS delete my files? No. Clearing the CMOS only resets your BIOS settings — like boot order, fan curves, and any overclock — back to factory defaults. Your drive and the files on it are untouched. It is one of the safest and most effective first steps for a hardware loop.
Can bad power really cause both kinds of loop? Yes, and this is why bootloops are so common here. Unstable mains makes a struggling PSU reset the board, which is a hardware loop. The same power cut striking mid-update corrupts Windows files, which is a Windows loop. A UPS plus a quality PSU prevents both — see our guide on a PC that will not boot after a power cut.
The One Thing to Remember
Every bootloop fix starts with one observation: does it restart before Windows, or after? Answer that first and you have already cut the problem in half. Before Windows means power, cooling, seating, and CMOS. After Windows means recovery, undoing the last update, and repairing system files. Diagnose in that order and you will rarely need to guess.
If you have worked through both halves and your PC still loops, the fault may be a dying PSU, a failing drive, or a board issue that needs hands-on testing. Build a system with us on quality, surge-resistant parts, or get in touch and our Lagos workshop will diagnose the loop and get you booting again.