# Computer clock running slow **URL:** \ **Category:** Factual Questions\ **Created:** [May 29, 2002, 3:15pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350 "2002-05-29T15:15:49Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Mr\_Creosote](https://avatars.discourse-cdn.com/v4/letter/m/74df32/32.png) [@Mr\_Creosote](https://boards.straightdope.com/u/Mr_Creosote)\ **Post date:** [May 29, 2002, 3:15pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/1 "2002-05-29T15:15:49Z")
I was hoping that someone out there could help with a puzzling feature of my computer. The clock insists on running slow. It usually loses about 15 mins over a couple of days. As far as I know I’m not running any programs that require hard core computing power. In case it’s relevant the computer is left on all the time and is reasonably modern (633MHz). ---
**Author:** ![Reeder](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@Reeder](https://boards.straightdope.com/u/Reeder)\ **Post date:** [May 29, 2002, 3:21pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/2 "2002-05-29T15:21:57Z")
It’s probably time to change your cmos battery. But if its not real bad [here is a program that will set your clock](http://www.worldtimeserver.com/atomic-clock/) to the Atomic Clock time. Easy to install, easy to use. ---
**Author:** ![Ill\_Logik](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Ill\_Logik](https://boards.straightdope.com/u/Ill_Logik)\ **Post date:** [May 29, 2002, 3:29pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/3 "2002-05-29T15:29:07Z")
I had the same problem with my computer. I called Gateway and they said there was no way that it could be the battery…and of course they sent me one anyway. It didn’t help at all. My clock actually lost about 5 minutes an hour no matter what I did. Gateway had no idea what to tell me, but one day it just fixed itself. To make sure it’s not the battery, wait until your clock is behind time, and restart your computer without setting the clock to the correct time. When I did this on my computer, the clock actually displayed the correct time after I restarted, but I’m not really sure what this means. ---
**Author:** ![Mr\_Creosote](https://avatars.discourse-cdn.com/v4/letter/m/74df32/32.png) [@Mr\_Creosote](https://boards.straightdope.com/u/Mr_Creosote)\ **Post date:** [May 29, 2002, 3:30pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/4 "2002-05-29T15:30:09Z")
Thanks Reeder. I’m not sure it is a battery problem since it has always happened. Think I’ll install the automatic time setting program though, that should sort it. Cheers Mr Creosote ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [May 29, 2002, 11:03pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/5 "2002-05-29T23:03:35Z")
Windows needs certain timing files to work. You can check to see if it has them I think by checking the time at the DOS prompt & compare it to the time that windows shows. When I changed a HD once, it didn’t get the files it needed so it did this too. ---
**Author:** ![Morbo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/morbo/32/389_2.png) [@Morbo](https://boards.straightdope.com/u/Morbo)\ **Post date:** [May 30, 2002, 1:00am UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/6 "2002-05-30T01:00:36Z")
> [@](#): > > \*Originally posted by handy \* > \*\*Windows needs certain timing files to work. You can check to see if it has them I think by checking the time at the DOS prompt & compare it to the time that windows shows. \*\* I’m sure this will come as a total shock to no one, but this post bears no basis in fact whatsoever. I suppose we should all be grateful that this thread wasn’t soliciting [medical advice](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=98401). :rolleyes: > [@](#): > > **Windows needs certain timing files to work.** Jibberish. Assuming you might mean the CMOS, (which has no “timing files,” but anyway), Windows doesn’t need anything from it. Without a valid CMOS battery, you will have to update the date and time every time you boot the machine, but Windows specifically can run without it. Assuming you might mean the BIOS, (which also has no “timing files”, but anyway), your machine won’t boot at all, with any OS, unless the BIOS has been flashed, which is probably what you encountered when you switched HDs, especially if the new HD was larger than the old one. > [@](#): > > **You can check to see if it has them I think by checking the time at the DOS prompt & compare it to the time that windows shows.** Meaningless. If you get a DOS prompt and type “time” - the time you get will be _identical_ to the time you get running in Windows, as it is pulled from the same place - the CMOS. Comparing the two would be about as useful as comparing your root directory in Explorer with the root directory in a DOS prompt by typing “dir.” To answer the OP, I would second **Reeder** ’s Atomic Clock suggestion first, and replacing the CMOS battery as a last resort. Just don’t make the mistake of taking **handy** ’s advice, which is, for the gajillionth time, nonsensical and irrelevant. Oh, and welcome to the boards! 🙂 ---
**Author:** ![John\_T.Conklin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_t.conklin/32/3307_2.png) [@John\_T.Conklin](https://boards.straightdope.com/u/John_T.Conklin)\ **Post date:** [May 30, 2002, 1:43am UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/7 "2002-05-30T01:43:59Z")
Sorry to break it to you, but computer clocks are notoriously bad. The crystal oscilator is probably less accurate than the one in the digital watches you might find in a cereal box. Plus it’s in an electrically noisy environment, which certainly can’t help. But that’s not all. If I recall correctly, the CMOS clock is only consulted at boot up and is used to set the initial value of a counter within the OS. From then on, it is incremented each time a periodic hardware interrupt is fired. I can no longer recall whether the PC architecture has this problem, but I do remember learning that some computer designs the interrupt heirarchy is such that some I/O devices have higher priority than the clock interrupt. Under high I/O load, clock interrupts can be lost, losing one clock tick. The same can happen on systems when a device driver blocks interrupts over the period when the timer interrupt would have triggered. You might want to look into running something to synchronize your time with a known good time source. If have a always-up network connection with consistant packet latency, you could set up a NTP client. Windows XP has it built in (they call it “internet time”). If not, you could use a GPS receiver. Check out [http://www.eecis.udel.edu/~ntp/](http://www.eecis.udel.edu/~ntp/) for details. ---
**Author:** ![ChuckForbin](https://avatars.discourse-cdn.com/v4/letter/c/ecb155/32.png) [@ChuckForbin](https://boards.straightdope.com/u/ChuckForbin)\ **Post date:** [May 30, 2002, 5:08pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/8 "2002-05-30T17:08:39Z")
You didn’t mention the hardware, but I had a similar problem with a nw Dell running XP Pro, and Norton Internet Security. The solution was to go into the Date/Time properties, then “Internet Time”, and uncheck the “Automatically synchronize with an Internet Time Server”. Remember, that’s “UNcheck”. Worked for me. Curious if it works for you. ---
**Author:** ![UncleBill](https://avatars.discourse-cdn.com/v4/letter/u/d26b3c/32.png) [@UncleBill](https://boards.straightdope.com/u/UncleBill)\ **Post date:** [May 30, 2002, 9:11pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/9 "2002-05-30T21:11:27Z")
**ChuckForbin** , my XP Dell has the same prob, will give it a whirl when I get home. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [May 30, 2002, 10:49pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/10 "2002-05-30T22:49:16Z")
Actually, **handy** ’s right on one thing - in some versions of Windows the “time” command at the DOS prompt, which interrogates the CMOS clock, and the display time on the Windows taskbar can be different, as the latter is based on an interrupt count started from the CMOS clock at boot time, as suggested by **John T. Conklin**. The procedure of comparing the “time” command result to the taskbar is given, in fact, in the MS knowledge base as a procedure for detecting a weak CMOS battery: [http://support.microsoft.com/default.aspx?scid=kb;EN-US;q189706](http://support.microsoft.com/default.aspx?scid=kb;EN-US;q189706) Note that this applies to Windows 95, 98 and Millenium. NT and 2000 periodically synch to the CMOS clock, and will thus lose time if the CMOS clock does. I don’t know what XP does by default. You can set up various services to synch to a master clock server, as has been mentioned, if it disturbs you. Personally, I accept the fact that real time clocks on PC’s aren’t the most accurate timekeeping instruments in the world, and I expect to have to reset them every so often. Probably made by the same people who make dashboard clocks in automobiles. ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [May 31, 2002, 2:21pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/11 "2002-05-31T14:21:52Z")
Well, I don’t know what the operating system is, so anything is a fair guess. But I have tested that stuff out to detect slow clocks on many computers with complete success. I have taken a HD from one computer (w95/98) & put it in another one only to get a slow clock. Do you know why? Because the HD didn’t have the timing files on it that the new computer needed, a reintstall put these files on. As for your Dell UncleBill’ “Dell has just come out with a time fix download. I also have a dell and had the same problem with the clock. The download fixed the problem. Check Dell support. Regards, Rd” That is for XP Also: “Double click the clock. XP can synch its clock with internet time. If this feature is not checked, check it. If it is checked, maybe it is not sychronizing correctly and you should use your computer’s clock and uncheck this feature. If this doesn’t fix it, replace your battery on your motherboard.” [http://computing.net/windowsxp/wwwboard/forum/20422.html](http://computing.net/windowsxp/wwwboard/forum/20422.html) ---
**Author:** ![Undead\_Dude](https://avatars.discourse-cdn.com/v4/letter/u/e19adc/32.png) [@Undead\_Dude](https://boards.straightdope.com/u/Undead_Dude)\ **Post date:** [May 31, 2002, 5:40pm UTC](https://boards.straightdope.com/t/computer-clock-running-slow/111350/12 "2002-05-31T17:40:35Z")
The XP solution is basically an ntp solution defaulted to use MS’s ntp servers. [Nettime](http://nettime.sourceforge.net/) is my personal favorite ntp client. It is simple to setup and very unintrusive. It should work on 95/98/ME/NT4/W2K/XP