Why PC clock isn't accurate?

Discussion in 'General Discussion' started by Rurouni, Jul 7, 2015.

  1. Rurouni

    Veteran

    Joined:
    Sep 30, 2008
    Messages:
    950
    Likes Received:
    216
    And it isn't just PC, but phone, car navigation, etc, if you don't sync them often, they will drift a lot (relatively speaking, vs my Casio watch that is still fairly accurate to the minutes after several years).
    Why is that happening? Can't they use a more accurate crystal or something? Why my cheap Casio is a lot more accurate even vs an expensive gadgets?
    Also I just adjusted the clock on my car navigation system (less than a month ago!), and it already drifted by minutes (forgot how much, probably around 2 or 3 minutes). I think I remember my phone's clock drifted similarly large when I forgot to use automatic date.
    Whyyyyy????? I don't ask for those clock to be as accurate as Casio, but at least be more accurate. Especially true for my car nav because it isn't connected with anything, thus can't sync time.
     
  2. UniversalTruth

    Veteran

    Joined:
    Sep 5, 2010
    Messages:
    1,747
    Likes Received:
    22
    I think it is because of the method they use in order to keep this time.

    For example, a Pentium 4 machine sucks - it is so terrible that after several hours, you can get a several minutes wrong reading.

    The processors of those gadgets suck.

    * But... a machine with C2Q is ok and I let it go with its own time updates - once per week or something...
     
  3. Rikimaru

    Veteran Newcomer

    Joined:
    Mar 18, 2015
    Messages:
    1,014
    Likes Received:
    395
    cpu is not used for clock. there is dedicated chip for this.
     
  4. UniversalTruth

    Veteran

    Joined:
    Sep 5, 2010
    Messages:
    1,747
    Likes Received:
    22
    OK, even so, I would still think that the central processsor has the influence on the process. Because when more work is done and respectively more load on the CPU, it gets worse then.

    BTW, if you know so much, why do you ask? :lol:
     
  5. Rikimaru

    Veteran Newcomer

    Joined:
    Mar 18, 2015
    Messages:
    1,014
    Likes Received:
    395
    What am I asking?
     
  6. Davros

    Legend

    Joined:
    Jun 7, 2004
    Messages:
    14,889
    Likes Received:
    2,304
    No thats why the clock still works when your pc is switched off
    If I was to guess I would think its temperature differences causing inaccuracies
     
    #6 Davros, Jul 7, 2015
    Last edited: Jul 7, 2015
  7. Bludd

    Bludd Experiencing A Significant Gravitas Shortfall
    Veteran

    Joined:
    Oct 26, 2003
    Messages:
    3,230
    Likes Received:
    798
    Location:
    Funny, It Worked Last Time...
    https://en.wikipedia.org/wiki/Crystal_oscillator

    also
    https://en.wikipedia.org/wiki/Frequency_drift
     
  8. Arwin

    Arwin Now Officially a Top 10 Poster
    Moderator Legend

    Joined:
    May 17, 2006
    Messages:
    17,682
    Likes Received:
    1,200
    Location:
    Maastricht, The Netherlands
    So PC heating up by hot GPU etc causes more drift
     
    Grall likes this.
  9. Grall

    Grall Invisible Member
    Legend

    Joined:
    Apr 14, 2002
    Messages:
    10,801
    Likes Received:
    2,172
    Location:
    La-la land
    Just enable to have your on-board clock set via an internet time server and you shouldn't need to worry about drift... :)

    ...In theory. In practice, I don't know how often the time server is actually polled, but hopefully drift shouldn't be so bad that it's more than a few seconds at most, even if the clock isn't set more than say, once or twice a week maybe.
     
  10. pcchen

    pcchen Moderator
    Moderator Veteran Subscriber

    Joined:
    Feb 6, 2002
    Messages:
    2,749
    Likes Received:
    127
    Location:
    Taiwan
    Mobile phones with GPS should be able to have very accurate time, because you need the precise time to triangulate.
     
  11. Davros

    Legend

    Joined:
    Jun 7, 2004
    Messages:
    14,889
    Likes Received:
    2,304
    They are possibly synced as well
    did you know that gps satellites clocks not only compensate for time dilation due to their fast speed (you probably do)
    but they also compensate for time dilation due to the fact they are in a varying gravitational field (elliptical orbit)
     
  12. Blazkowicz

    Legend Veteran

    Joined:
    Dec 24, 2004
    Messages:
    5,607
    Likes Received:
    256
    For computers where this is critical (servers) the daemon (service) that is responsible for synching the clock may employ a scheme where the time drift is gradually compensated. I don't want to think too much about the mess if your data records, logs or whatever jump back and forth in time.


    Even on a desktop these days you might need accurate time (at least within an hour or 10 minutes) : encryption or security protocols may depend on it. This has dramatic effect on some networks. There was that 9-year-old PC that couldn't access youtube (except very bastardized raw html not good for anything at all) or much anything else. Really weird ass problem. So it did local music playing duties.
    Only when I later found out the battery was dead did I try to set the time and date (I believe it thought it was in january 1980), and everything worked again.
    With another PC, no way to pass the "captive proxy portal" even!
    Both times I used a sudo rdate [name of reachable-on-the-LAN time server], which is about equivalent to Windows getting time from the network.


    Really weird that replacing a Cr2032 coin battery fixes networking issues, but it's really needed.
     
    Grall likes this.
  13. Alexko

    Veteran Subscriber

    Joined:
    Aug 31, 2009
    Messages:
    4,495
    Likes Received:
    910
    I guess that when my mother used to tell me I was throwing time away by playing video games, she was more right than she knew.
     
    digitalwanderer and Arwin like this.
  14. Grall

    Grall Invisible Member
    Legend

    Joined:
    Apr 14, 2002
    Messages:
    10,801
    Likes Received:
    2,172
    Location:
    La-la land
    That does indeed sound most vexing! :) Never had that issue myself, as nothing I do is that critical.

    Lol! Your mumster was wiser than you gave her credit for at the time I bet. ;)
     
    digitalwanderer likes this.
  15. Rurouni

    Veteran

    Joined:
    Sep 30, 2008
    Messages:
    950
    Likes Received:
    216
    Although my phone and home pc connected to the Internet, the pc on my office isn't and also the audio video head unit on my car isn't connected to internet.
    Anyway, do you guys know how to sync clock on multiple PCs connected with in a Windows workgroup (basically simple file sharing?). All the PCs are using Windows 7. The PCs is in a LAN that isn't connected to the internet. What I want is for PCs in the network to be able to at least sync their time with one of the PC. I have searched and couldn't found a reliable solution. I thought that this kind of basic thing should be easy, unfortunately it isn't (or maybe I'm lacking in my Google-fu). The simplest thing in my mind would be making one of the PC act like a time server and let other PC point their time server update to it, but there isn't an obvious way to make a Windows 7 PC acts as a time server. I've tried using a free app that can act as a time server, but strangely, sometimes the PCs can sync to it, sometimes not. I don't know what cause it, but I just can't figure out why it can't sync reliably.
     
  16. Grall

    Grall Invisible Member
    Legend

    Joined:
    Apr 14, 2002
    Messages:
    10,801
    Likes Received:
    2,172
    Location:
    La-la land
    Why not just let all your LAN clients synch over the internet...? It's just a checkbox to enable, which might actually be enabled by default these days, and it tends to work pretty well too. :)
     
    digitalwanderer likes this.
  17. Davros

    Legend

    Joined:
    Jun 7, 2004
    Messages:
    14,889
    Likes Received:
    2,304
    Also altitude affects time, although you need an atomic clock to measure it
     
  18. Rurouni

    Veteran

    Joined:
    Sep 30, 2008
    Messages:
    950
    Likes Received:
    216
    Because the PCs isn't connected to the Internet.
     
  19. Blazkowicz

    Legend Veteran

    Joined:
    Dec 24, 2004
    Messages:
    5,607
    Likes Received:
    256
    I would install a lightweight linux in a virtualbox VM (e.g. debian + lxde or lubuntu), enable "bridged networking" in Virtualbox and try to get a time server working.
    There's a package simply called "ntp", and "ntp-doc" with some help in it, well I guess it's the kind of help from Unix manuals

    Lots of details/concepts here
    https://en.wikipedia.org/wiki/Network_Time_Protocol

    Also


    Something that could happen to you in theory : if you do file synchronization, especially P2P synchronization between two desktop computers for example, bad things can happen. Like, the "older" file is overwritten with the contents of the "newer" file.
    With dropbox et al. perhaps the implementation is less naïve, or at least dropbox's servers are set to the correct time so there's less chance for a mess.
     
  20. Grall

    Grall Invisible Member
    Legend

    Joined:
    Apr 14, 2002
    Messages:
    10,801
    Likes Received:
    2,172
    Location:
    La-la land
    The risk exists of course, but you would have to write changes to the file inside of a rather small window (probably seconds only), unless your clock has drifted abnormally. Under normal circumstances, drift should never get big enough to pose any major risk for us mere mortal PC users... :)
     
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...