Why PC clock isn't accurate?

Rurouni

Veteran
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.
 
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...
 
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...
cpu is not used for clock. there is dedicated chip for this.
 
cpu is not used for clock. there is dedicated chip for this.

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:
 
I would still think that the central processsor has the influence on the process.
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
 
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https://en.wikipedia.org/wiki/Crystal_oscillator

A crystal's frequency characteristic depends on the shape or 'cut' of the crystal. A tuning fork crystal is usually cut such that its frequency over temperature is a parabolic curve centered around 25 °C. This means that a tuning fork crystal oscillator will resonate close to its target frequency at room temperature, but will slow down when the temperature either increases or decreases from room temperature. A common parabolic coefficient for a 32 kHz tuning fork crystal is −0.04 ppm/°C².

dadfc363c6d0038be5c6d63897a364c8.png

In a real application, this means that a clock built using a regular 32 kHz tuning fork crystal will keep good time at room temperature, lose 2 minutes per year at 10 degrees Celsius above (or below) room temperature and lose 8 minutes per year at 20 degrees Celsius above (or below) room temperature due to the quartz crystal.

also
https://en.wikipedia.org/wiki/Frequency_drift
 
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.
 
Mobile phones with GPS should be able to have very accurate time, because you need the precise time to triangulate.
 
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)
 
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.

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.
 
I don't want to think too much about the mess if your data records, logs or whatever jump back and forth in time.
That does indeed sound most vexing! :) Never had that issue myself, as nothing I do is that critical.

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.
Lol! Your mumster was wiser than you gave her credit for at the time I bet. ;)
 
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.
 
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. :)
 
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

That does indeed sound most vexing! :) Never had that issue myself, as nothing I do is that critical.


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.
 
Like, the "older" file is overwritten with the contents of the "newer" file.
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... :)
 
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