Why aren't computer clocks as accurate as cheap quartz watches?

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

Maybe the same reason we didn't have built-in clocks until after there
were five dollar LCD wris****ches. I don't know.

My current clock is very accurate (MSI mainboard).

wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.


Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.
Vendors care if you send it back. They don't care if you
bitch on the internet.
mike

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wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

I've often wondered the same thing...also why a $9 alarm clock will have
provision for battery backup, but $200 VCR (back when VCRs were $200)
needed to be rweset with each blip in the mains voltage.

FWIW, there are utilities which will update your computer clock from the
National Bureau of Standards over the web.....

jak

On 26 Oct 2005 15:03:04 -0700, wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.

That question have been around for more than 20 years and probably
longer. Even one PC magazine reported a major branded PC that used to
cost $2,000 couldn't keep time as well as a $5 watch from Kmart (not
exact quote but similiar to that)

The OS could check via internet at regular intrevials to make
correction to the clock but that is if the PC does have internet
connection at all.
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To reply, replace digi.mon with phreaker.net

somebody wrote
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

Who is the manufacturer? I only use Gigabyte(mostly) or MSI (sometimes)
motherboards. I find the clocks to be reasonably accurate. My guess
would be that the OEM didn't ground the crystal case or use the proper
guard ring techniques for noise reduction. Do you find that they run
fast or slow?

wrote:
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.



I have one PC that will lose or gain hours at a time if the machine goes
into standby, another that does ok but still drifts enough that I have
to use a utility to keep it in sync with the atomic clock. On the other
hand a Sun workstation that I fire up occasionally to play with keeps
excellent time, even after sitting unplugged for 6 months it's usually
within a few seconds but then it was originally $25K.

In article . com,
wrote:

Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.


Dunno if it's still true in PC-land - I've been living in a Mac world
for a LONG time now - but when I was playing with them years ago, the
battery-backed real-time clock was read once at startup to set the
computer's software clock, which then kept time by counting clock
interrupts generated by the motherboard timing circuitry. That
interrupt, like any other "not non-maskable" interrupt, can be blocked
out for various reasons by various things, causing the software clock to
lose time. Usually, the amount of "lost" time isn't really noticable
except on "continuously on" machines. But with long periods between
restarts, heavy use of software (or firmware... The blame may not be in
your clock, but in your ROM code) that disables interrupts often or for
extended periods, and/or no intervention (be it human or software)
happening, it can grow to substantial amounts of time surprisingly quick.

Immediately after startup, the clock SHOULD be reasonably close to
right, since it will have been freshly set from the battery powered
clock, but after a while, it *WILL* go wonky unless steps are taken to
correct the drift - It's just the nature of the beast.

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mike wrote:

Supply and demand.
If your watch kept bad time, you'd send it back.
If your computer keeps bad time, you'll reset the clock
and bitch about it on the internet.

I'm looking for a techical explanation.

James Sweet wrote:

I have one PC that will lose or gain hours at a time if the machine goes
into standby, another that does ok but still drifts enough that I have
to use a utility to keep it in sync with the atomic clock. On the other
hand a Sun workstation that I fire up occasionally to play with keeps
excellent time, even after sitting unplugged for 6 months it's usually
within a few seconds but then it was originally $25K.

The only PC motherboards I've seen that consistently kept accurate time
all had Dallas clock chips in them, and some of those chips were still
running properly from their internal lithium cells (permanently
encapsulated) 10 years later.