Computer Clock Showing the Wrong Time? Why It Keeps Changing or Resetting — and How to Fix It

The clock in the corner of your screen is wrong. Maybe it's off by a few minutes, maybe by whole hours, or maybe — the frustrating one — it looks fine while you're working but snaps back to a strange old date every time you restart or unplug the machine. It seems like a trivial cosmetic glitch, but a wrong clock quietly breaks more than the time display, so it's worth fixing properly.

The good news is that most cases are one setting you can toggle in under a minute. The important part is telling apart the three very different situations, because each has its own cause: a clock that's slightly off (a sync problem), a clock that's wrong by an exact number of hours (almost always the time zone), and a clock that resets to a fixed old date every single time you power down (that's hardware, and it's a cheap fix). This guide walks all three, plus the surprise cause that trips up anyone dual-booting Linux — and, honestly, why you shouldn't install any "PC time fixer" download to sort out something Windows and a coin battery handle for free.

One quick note on why this matters, so you recognise the symptoms: a badly wrong clock is a common hidden reason secure websites won't load ("Your connection is not private"), sign-ins loop endlessly, app downloads stick on "waiting," and things like iMessage won't activate. If you landed here from one of those, fixing the clock below may be the whole answer.

Start here: turn on "Set time automatically"

For a clock that's simply drifted off — a few minutes or seconds out — the fix is to let Windows keep it in sync with an internet time server instead of trusting the PC to keep time on its own. Right-click the clock and choose "Adjust date and time," or go to Settings > Time & language > Date & time. Turn on "Set time automatically." While you're there, click "Sync now" under Additional settings to force an immediate update.

If "Set time automatically" is already on but the time is still wrong, toggle it off, wait a few seconds, and turn it back on — that often nudges a stuck sync. If it corrects itself and then drifts again over days, that's normal on some machines and the "Sync now" button or the deeper fixes further down will settle it. If it corrects itself but then resets to a totally wrong old date every reboot, skip ahead to the CMOS battery section — that's a different problem entirely.

Off by exactly an hour or several? It's the time zone

If the minutes are right but the hour is wrong — off by exactly one, two, or three hours, say — the time itself is fine and the time zone is set wrong. This is extremely common after travelling, setting up a new PC, or when a laptop guesses your location incorrectly. In Settings > Time & language > Date & time, either turn on "Set time zone automatically," or, if that keeps picking the wrong place, turn it off and choose your zone by hand from the "Time zone" drop-down (for us that's Pacific Time — (UTC-08:00) Pacific Time).

One catch worth knowing: "Set time zone automatically" relies on Windows Location services. If location is switched off, Windows can't work out where you are and may sit on a wrong zone. So either turn Location on (Settings > Privacy & security > Location) so auto-zone can do its job, or just set the zone manually and leave the automatic option off. Don't forget the "Adjust for daylight saving time automatically" toggle on the same screen — if that's off, your clock will be an hour out for half the year.

When it won't sync: the Windows Time service

If "Set time automatically" is on but the clock still won't correct itself, the background service that does the syncing may have stopped. Press Windows key + R, type services.msc, and press Enter. Scroll to "Windows Time," and if it isn't running, right-click it and choose Start; double-click it and set "Startup type" to Automatic so it comes back after a reboot.

If it still won't behave, a clean re-registration usually does it. Open Command Prompt or Terminal as administrator (right-click Start > Terminal (Admin)) and run these one at a time: net stop w32time, then w32tm /unregister, then w32tm /register, then net start w32time, then w32tm /resync. That tears down and rebuilds the time service and forces a fresh sync.

Occasionally the default time server itself is unreachable. Open Control Panel (the old one — search "Control Panel"), go to Clock and Region > Date and Time > Internet Time tab > Change settings, and try a different server such as time.nist.gov or pool.ntp.org instead of the default time.windows.com, then click "Update now." A different, healthy server often syncs immediately when the default won't.

The dead giveaway it's hardware: the CMOS battery

Here's the one that isn't a setting at all, and the tell is unmistakable: if your clock is correct while the computer is on, but resets to a fixed, obviously-wrong old date every time you shut down or unplug — commonly something like the year 2009, or a manufacturer date, or even 1970 or 1980 — the little coin-cell battery on the motherboard is dead. That battery (a CR2032, about the size of a nickel) keeps a trickle of power to the chip that remembers the date, time, and your firmware settings while the machine is off. When it dies, the clock has nothing to run on between power-offs and starts from scratch each boot.

A few corroborating signs confirm it: the machine may also forget BIOS/UEFI settings between boots, you might see a message at startup like "CMOS checksum error," "System battery voltage is low," or "Press F1 to continue," and the reset date is always the same rather than randomly drifting. If that matches, no software fix will help — the fix is a new battery.

The battery costs a couple of dollars and lasts around ten years, so it's a very cheap, very final fix. On a typical desktop tower it's a genuinely easy swap: power off, unplug, open the side panel, gently pop the old coin cell out of its clip and press a new one in the same way up (the "+" side faces out). Laptops are another story — the battery is often buried deep inside, sometimes under the motherboard or wrapped and connected by a little cable, so on most laptops this is a job worth handing to someone who opens them for a living rather than prying the case apart. Either way, after replacing it you'll want to go back into Settings and set the time (and re-check any BIOS settings that reset).

The surprise cause: dual-booting with Linux

If you run both Windows and Linux on the same computer, there's a classic reason the Windows clock ends up wrong — usually off by exactly your UTC offset — every time you switch back from Linux. The two systems disagree about what the hardware clock means: Windows assumes it's set to your local time, while Linux assumes it's set to UTC (universal time) and applies an offset. Boot into Linux, then back into Windows, and Windows reads the now-UTC hardware clock as if it were local — so it's off.

The cleanest fix is to make the two agree. The usual approach is to tell Windows to treat the hardware clock as UTC, the way Linux does, by adding a registry value. In an administrator Command Prompt, run: reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /d 1 /t REG_DWORD /f, then reboot. (Editing the registry is an advanced step; if you're not comfortable, the alternative is to set Linux to use local time instead — either side works, as long as both machines make the same assumption.) If you don't dual-boot, this section doesn't apply to you.

Why a wrong clock breaks more than the clock

It's worth understanding why a small thing like the wrong time causes such outsized trouble, because it explains a lot of otherwise-baffling errors. Secure connections — the padlock "https" on nearly every website now — depend on a certificate that's only valid between two dates. Your computer checks that against its own clock, so if the clock is badly wrong, every certificate looks either expired or not-yet-valid, and your browser throws "Your connection is not private" or NET::ERR_CERT_DATE_INVALID on sites that are perfectly fine. A laptop that resets to 1970 will fail to load almost the entire modern web until you fix the date.

The same time-based handshake underpins signing in to accounts, syncing cloud storage, activating iMessage, and downloading apps and updates — all of which can quietly fail or loop when the clock is off, usually with an error that points nowhere near the real cause. That's why our guides to Wi-Fi that's connected but has no internet, to app downloads stuck on "waiting," and to iMessage stuck on "Waiting for Activation" all send you here to check the clock first. Fix the time, and a surprising number of unrelated-looking problems clear up at once.

How we can help

Most wrong-clock cases are a two-minute settings fix you can do yourself, and we'd always rather point you at the free toggle than sell you anything — there is no such thing as a legitimate "PC clock repair" download, and any that advertise themselves as one are best avoided. But when the clock resets every single reboot, that's the hardware talking, and replacing a CMOS battery is exactly the kind of quick, inexpensive fix we do for people across Southern California and the Coachella Valley — a couple of minutes on a desktop, and safely done on a laptop we'd otherwise worry about you cracking open.

If you've turned on "Set time automatically," re-registered the time service, and the clock still won't hold — or it keeps snapping back to some year long past — bring it in and we'll swap the battery, confirm the firmware settings survived, and get you back to a computer that knows what day it is (and can therefore load secure sites and sign you in again).