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Windows 10 clock is constantly lagging behind

My system clock is constantly getting out of sync. I have no idea how or why this started happening. I first noticed it yesterday evening. I checked that the time zone was OK, and synced manually. After some time, I noticed that the clock was behind again, so I synced again… And this happened again and again. I probably synced my clock more than 10 times during the last 24 hours.
I constantly checked the time and compared it to my ipad during the day. It did not look, that it was “going slower” and lagging behind bit by bit. It stayed OK for some time, then suddenly it was way behind. Sometimes hours behind. And sometimes it went out of wack mere minutes after the manual sync. It kinda felt, like the clock simply stopped at some point.

For example, take a look at the screens below.


I synced the clock and left home for some errands. The PC was idle all this time. When I came back at 8 PM and checked the clock - it was 4 hours behind :worried:

And I know it has nothing to do with AFK. My PC is always ON and it never sleeps (Sleep set to Never). Also, the clock goes out of sync, even when I’m not AFK, and I’m doing something on the PC at that moment. I simply compare time to the ipad and… it’s behind.

What happened yesterday

Well, nothing particularly special happened yesterday. Only 2 things come to mind.

  1. I manually changed the time on my unRAID server. I noticed it was 2 hours of, and manually changed Pacific to Eastern timezone. I am linux newb, and have no idea why this happened on unraid. But it happened to me before, and I fixed it exactly the same way.
  2. My windows activation expired. I used Microsoft Toolkit to activate for years, but MTK was abandoned some months ago. I had windows warnings about expiration for some time now, I ignored it. But yesterday I finally got the Activate Windows in the bottom right of the screen. I am in process of looking for the MTK replacement (probably KMS_VL_ALL).

Help, please

I really really do not want to re-install windows at this time. It has been 3+ years since my last clean install and it will take me a week to get things backed up, and re-installed, and tweaked back the way I like it.

If you need any more info, please lemme know.

Thanks in advance for any help.

I’m imagining that the CMOS battery is loosing juice.

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Is this battery anything special? I mean where could I buy the replacement as fast as possible?

Current (presumably bad) battery

Heh, CMOS battery was the only thing kinda maybe that could explain this, that I have found by googling. But I thought, that this battery was keeping time only when PC is powered off?

I mean, does the CMOS battery keep time in windows, when the machine is powered on? Really?
Just interested, why it would work like that…

You could always get one at Walgreens or maybe any supermarket. But hold off on that because it could be maybe software related to how windows does time syncing.

You can view sync stats by using

w32tm /query/status

From CMD


I rummaged through my batteries and found this. Did I get lucky? Would this battery be OK as a replacement?
Sorry if the question seems silly. I am clueless about batteries, and want to make sure.

Any 3V CR2032 battery should do the trick. I think all motherboards use them

Need a space between /query and /status
And the result:


Should I set this to Automatic?

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I would assume that is what is causing your issue. Not sure why it would be set to manual anyways.

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Yes. Set that to auto:

My bad.

By default Windows Time is set to manual I believe (my personal and work computer are that way), but it should also be triggered by the OS to run periodically.

And yes, that Energizer battery should be fine.

By default, Windows is configured to ping a Microsoft NTP server and while I can’t remember the details, it seems to me that this doesn’t happen very frequently. While you’re under the hood, mucking about, you might be interested in pointing your machine at a NTP pool (unless, of course you have a time server on your network) and configuring the update frequency for better performance.

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I’ve started the Windows Time service and set it to Automatic. It’s been about 12 hours, since I’ve done it, and the time is still OK.
Before it always gone out of sync in less than half an hour.
I guess, my problem has been fixed.

Thank you @Goalkeeper for pointing me to the solution.
Thank you everyone for all your help.

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Try to keep services connected to the internet at a minimum to reduce your attack vector according to security experts. This is particularly true for MS Windows.

If you are not running time-sensive/time-critical applications, synchronizing the time once, should suffice.


Excellent point. My pfSense router/firewall acts a my network time server and port 53 is completely blocked (as are most of my firewall ports) for all other machines.

A default deny policy on both sides of the firewall is the best approach in these dark times. It’s a jungle out there!

EDIT: Ha ha, thinking about NTP, but writing DNS port … doesn’t matter I have DNS blocked too! ; )

I keep a local one myself that syncs super frequent (raspi) and the specific connection packets themselves get first absolutely priority on the network so that I just sync all the systems to the rpi…

Makes for stupid accurate time… especially if you specify a small pool of the absolute closest time servers too you…


Looking into it more. Alternatively you could go back and try it again on manual, but this time stop and then unregister the service, then start the time service again by using:

  • net stop w32time
  • w32tm /unregister
  • w32tm /register

Quick note, you can apparently use windoms keys that have been registered to 10 from machines with earlier os’s on them. So, example, my thinkpad has a windows 7 key on it, and burned to uefi. I installed 10 on it, it registered, then I needed a key for my mac pro, so I just used my thinkpad’s key and it worked.

I don’t think the key system really has any rules, so it probably doesn’t matter where the key comes from.

Just thought I’d share.

In 2019, it becomes more important to control network traffic on an end machine per application and less on a central point. If you live in a cloud of paranoia, a firewall alone is not enough.

The fact that you block most things is one thing but it doesn’t change the fact that you have allowed some traffic. Even if tcp 443 … if you have a parasite in the network, you may not even see in time that something is leaking.
But it’s already offtop.

The world is a damn jungle, buy ak47 and be ready for zombies.

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The zmbies are real!!!

No question … just because the traffic is going over port 443, that doesn’t make it “safe” traffic. I won’t share my entire strategy, but I have several different VLANs with varying degrees of trust. Clients on the untrusted VLANs enjoy no Internet access whatsoever, on any of the firewall ports.

An air-gaped network is the only moderately safe approach and even then, if a state actor wants to compromise you, it’s only a matter of time.

I have the exact problem as @cryodream except instead of Windows clock being a few hours behind it’s a few hours ahead. Thanks, @cryodream for sharing I will have to try the solution in this post.