Why Does My Computer Keep Restarting by Itself? (Windows 11 Random Reboots)

Few things are as unsettling as a computer that just restarts itself. You're in the middle of something — a game, a spreadsheet, a video call — and without warning the screen goes black, the fans spin up, and you're staring at the Windows logo again, work gone. Sometimes it happens once a week; sometimes it's every twenty minutes, or the machine won't even stay on long enough to log in. And the maddening part is that there's usually nothing on screen to explain it: no blue screen, no error, no clue. So it feels random and personal, like the PC has a mind of its own.

It almost never is random. A computer restarting by itself is Windows or the hardware hitting a problem serious enough that the safest response is to reboot — and the reason it looks like it comes from nowhere is that, by default, Windows restarts so fast you never see the error it was trying to show you. The good news: you can make it stop and reveal that error, and once you can see what's happening, the cause usually narrows down quickly to one of a short list — heat, power, a driver, memory, or an update. Before any of that, one thing to skip: the "PC repair," "system booster," and "fix-it" tools advertised all over these search results. A random reboot is almost always a physical or driver problem, and no cleaner app can find a clogged heatsink, a tired power supply, or a loose stick of RAM. Everything below is a real diagnostic step, and most of it is free.

First: make Windows show you the error instead of hiding it

This is the single most useful thing you can do, and almost nobody knows about it. Out of the box, Windows 11 is set to automatically restart the moment it crashes — which means if a real error (the crash screen that used to be blue and is now black) is behind your reboots, the PC flashes it for a fraction of a second and reboots before you can read the one detail that would tell you what's wrong. Turn that off and the next crash will stop and wait, showing you a "stop code" you can actually write down.

To do it, press the Windows key + R, type sysdm.cpl and press Enter. Go to the Advanced tab, and under "Startup and Recovery" click Settings. In the "System failure" section, untick "Automatically restart," click OK, and you're done. Nothing bad happens in day-to-day use — this only changes what the PC does when it crashes. Now, instead of a mystery reboot, you'll get a crash screen that stays put with a stop code and often the name of the file or driver that failed. That single line turns "it randomly restarts" into a searchable, fixable problem — and if you do start seeing a stop code, our guide to reading the Windows 11 crash screen walks through what the common ones mean.

Check the crash history: Reliability Monitor

Windows quietly keeps a diary of its own bad days, and it's the fastest way to spot a pattern. Press Windows key + R, type perfmon /rel and press Enter (or just search the Start menu for "reliability" and open "View reliability history"). You'll get a day-by-day timeline going back up to a year, with a red X on any day something crashed. Click a red X and you'll see entries like "Windows was not properly shut down" or a specific app or hardware failure, often with technical details you can expand.

What you're hunting for is a pattern, because the pattern names the cause. Do the reboots line up with a particular program or game every time? That points at software or a driver. Did they start the day after a Windows update or a new driver installed? That's your suspect — you can roll that update back. Are they scattered with no software link, especially under load or heat? That leans toward hardware — power, memory, or temperature. Five minutes in Reliability Monitor often saves you from changing things at random, which is how most people make a reboot problem worse.

Is it restarting, shutting off, or looping?

These feel like the same problem but they point in different directions, so it's worth being precise about what yours does. A PC that runs fine and then reboots at seemingly random moments is usually a driver, an update, or intermittent memory trouble. A PC that reboots specifically when you push it — launching a game, rendering video, running something demanding — is almost always heat or power, because those are the moments the machine draws the most from both. And a PC that won't stay on long enough to reach the desktop, cycling through the logo over and over, is a boot loop, which is a deeper problem (a bad update, corrupted system files, or failing hardware) that often needs the recovery tools rather than a quick setting.

Two more distinctions save people a lot of wasted effort. If the machine truly powers all the way off and comes back on — or shuts off and refuses to restart at all for a moment — suspect the physical power feed: a loose cable, a wall outlet or power strip that's flaky, or the power supply itself. But if it only misbehaves when you tell it to shut down (you pick Shut Down and it restarts instead), that's usually a harmless Windows quirk tied to the "Fast Startup" feature or a "restart on shutdown" setting, not a hardware fault — a different and much less worrying issue than spontaneous reboots while you're using it.

Overheating: the most common hardware cause

When a computer restarts under load — during games, video, or anything that works it hard — heat is the first thing to suspect. Every PC has hard temperature limits built into its processor and graphics chip; when they're about to be exceeded, the machine cuts power instantly to protect itself rather than cook its own components. That emergency shutoff looks exactly like a random restart. On a desktop the usual culprit is years of dust packed into the heatsink and fans, a CPU fan that has stopped spinning, or thermal paste that has dried out; on a laptop it's blocked vents and a clogged fan, which we cover in depth in our summer-overheating guide.

There's a real Southern California angle here. In a hot garage office, a sunroom, or any room without strong air conditioning, the air the computer pulls in to cool itself is already warm — and out in the Coachella Valley, where summer afternoons run past 110°F, an un-cooled room can push a PC over the edge doing very little. If the reboots are worse in the afternoon, worse in summer, or only happen when the machine is busy, treat it as heat: blow the dust out of a desktop's vents and fans with a can of compressed air, make sure every fan is actually spinning, give the machine breathing room, and cool the room. If it's a desktop that's never been cleaned inside, that alone fixes a lot of "random" reboots.

Power: a failing or overloaded power supply

On a desktop, the power supply — the box the wall cord plugs into — is a quiet, common cause of self-restarts, and it's the one the software crowd never mentions. A power supply that's aging, underpowered, or starting to fail can deliver clean power at idle but stumble the instant the PC demands more, so the machine reboots exactly when you load it up: a game, a big export, a graphics card working hard. This gets especially common after someone adds a power-hungry new graphics card to a PC whose supply was only ever sized for the old one. A failing supply generally isn't a home fix — it's an inexpensive part but it needs to be diagnosed and swapped on the bench — but it's worth knowing it's a prime suspect for load-triggered reboots.

Before you assume the worst, though, rule out the cheap stuff, because a wobbly power feed causes the same symptom. Make sure the power cable is firmly seated at both ends, plug the computer straight into a known-good wall outlet instead of through a daisy-chained power strip, and see if the reboots stop. Flaky outlets, overloaded strips, and the brownouts and voltage dips that come with a strained summer power grid can all knock a PC offline in an instant — which is also the argument for running any desktop through a decent surge protector, or better, a small battery backup (UPS) that rides out the dips. If reseating the cable and changing the outlet clears it up, you've saved yourself a hardware hunt.

Drivers — especially the graphics driver

A driver is the small piece of software that lets Windows talk to a piece of hardware, and a buggy one can crash the whole system hard enough to reboot it. The graphics driver is the usual offender, because it's complex and it's under the most strain exactly when people report reboots: in games and video. If your PC restarts during graphics-heavy tasks and Reliability Monitor or the stop code points at a display driver, the fix is to get a clean, current driver straight from the graphics maker (Nvidia, AMD, or Intel) rather than trusting Windows to have the latest — and sometimes to fully strip the old driver out first before reinstalling. We walk through that clean-reinstall process in our guide to fixing games that crash to the desktop.

It isn't only graphics. If the reboots started right after you installed a new device, a new driver, or a driver "updater" utility, that new arrival is your first suspect — roll it back or uninstall it and see if the machine steadies. This is where the Reliability Monitor timeline pays off again: if the red X's begin the day a driver changed, you don't have to guess.

Bad memory (RAM)

Faulty memory is a classic cause of restarts and crashes that seem to come from nowhere, because bad RAM misbehaves unpredictably — fine for hours, then a corrupted read that Windows can't recover from, and down it goes. If your reboots are scattered with no software pattern, or you're now seeing crash screens with memory-related stop codes, test the RAM. Windows has a built-in tester: press Windows key + R, type mdsched.exe, press Enter, and let it restart and run a memory check before Windows loads. If it reports errors, you've very likely found your cause.

On a desktop, before you buy anything, it's worth reseating the memory — powered off and unplugged, press each stick firmly back into its slot, as a module that has worked slightly loose can cause exactly this. If the tester flags a specific stick, replacing it is straightforward and cheap. Memory that's been manually sped up (an "XMP" or overclock profile in the firmware) can also cause instability; if someone set that up, returning it to default settings is a quick thing to try. If you're not comfortable inside the case, this is a good point to hand it to someone who is.

When it's Windows Update — not a fault at all

Not every self-restart is a problem. Windows 11 installs updates in the background and then reboots to finish them, and if that happens while you're away — or catches you off guard — it can look exactly like a spontaneous restart, except your work may be sitting there reopened afterward. You can tame this: go to Settings > Windows Update > Advanced options and set your "Active hours" to the times you actually use the PC so it won't reboot on its own during them, and turn on "Notify me when a restart is required to finish updating" (it's off by default), so Windows warns you first instead of just going for it.

The flip side is that a bad update can genuinely cause repeated reboots. If your trouble started right after an update installed — and Reliability Monitor will show you the date — you can uninstall that specific update or use System Restore to roll back to just before it, then pause updates for a week while the fix lands. And keep the honest opposite in mind too: an out-of-date Windows or a missing driver update is sometimes the cause, so if you're behind, letting it fully update (at a time that suits you) is worth doing before you go chasing hardware.

Malware and something you installed

Occasionally the cause is software you didn't want. Some malware deliberately forces restarts, and a badly behaved program or "optimizer" installed right before the trouble began can do it by accident. If the reboots started after you installed something — or after a sketchy download — that's your first suspect: uninstall it, or use System Restore to go back to before it arrived. It's also worth running a full scan with Windows Security or your antivirus to rule out an infection, which we cover in our guide to scanning Windows for viruses.

The theme across all of this is the same: a computer restarting by itself is trying to tell you something, and the trick is to stop it hiding the message. Turn off the automatic restart so you can read the crash, check the Reliability Monitor timeline for a pattern, and then follow the pattern to heat, power, a driver, memory, an update, or something you installed. Work through those in order and most people find the culprit without spending a cent.

How we can help

The honest short version: don't buy a "PC fixer" tool for a computer that restarts on its own — it can't see the actual causes. Instead, flip off the automatic restart (Windows key + R, sysdm.cpl, Advanced, Startup and Recovery) so the next crash shows its stop code, open Reliability Monitor to find the pattern, and let that pattern point you at heat (dust and fans, worse in the SoCal summer), power (a tired supply or a flaky outlet), drivers (usually graphics), memory (run mdsched.exe), or a recent update or install you can roll back. That covers the large majority, for free.

But some of these — a failing power supply, a bad stick of RAM, a desktop that needs a proper clean-out and fresh thermal paste, or a boot loop that won't reach the desktop — are genuinely a bench job, and there's no shame in handing it over rather than opening the case yourself. That's exactly the kind of everyday computer trouble we sort out for homes and small businesses across Southern California and the Coachella Valley: diagnosing whether a self-restarting PC is heat, power, memory, or software, doing the repair or the part swap if it needs one, and telling you honestly when a machine is worth fixing versus replacing. Because we don't sell you software subscriptions, we've no reason to point you at anything but the actual fix.