Any way to upgrade CMOS clock??

  • Thread starter Thread starter maruk2
  • Start date Start date
M

maruk2

As the starting point, assume a PC with Intel Core-2 6300
at 1.86GHz, 32-bit Vista

The CMOS clock (is it still called CMOS clock?) drifts about
2 secs/day on my machine. Is there any way to replace it
with a much more precise clock? Are there any expansion
cards available with high quality clocks to replace
the default CMOS clock. I do not want the drift to
exceed 1 second/week.

Please do not bring up the synchronization issue with
Internet servers. I want to synchronize only once/week
at the most and not every day.
 
As the starting point, assume a PC with Intel Core-2 6300
at 1.86GHz, 32-bit Vista

The CMOS clock (is it still called CMOS clock?) drifts about
2 secs/day on my machine.
Click to expand...

That's very accurate as motherboard clocks go. Consider yourself
lucky.

There's no way to replace a clock on a modern motherboard. If
you don't mind paying way too much for a clock card:

http://www.beaglesoft.com/clcahome.htm
 
As the starting point, assume a PC with Intel Core-2 6300
at 1.86GHz, 32-bit Vista

The CMOS clock (is it still called CMOS clock?) drifts about
2 secs/day on my machine. Is there any way to replace it
with a much more precise clock?
Click to expand...

You could add trimmer capacitors to the 32.768kHz and 14.31818MHz
crystals. The original IBM AT had a trimmer cap for the latter.
Are there any expansion
cards available with high quality clocks to replace
the default CMOS clock. I do not want the drift to
exceed 1 second/week.
Click to expand...

AIUI, the RTC/CMOS RAM chip provides the initial hardware time
reference using the 32.768kHz crystal. After bootup, the 14MHz crystal
takes over and provides the reference for a "software" clock.
Please do not bring up the synchronization issue with
Internet servers. I want to synchronize only once/week
at the most and not every day.
Click to expand...

If you are losing time after synchronising with an Internet time
server, then I'd suspect that the 14MHz crystal needs trimming.

- Franc Zabkar
 
Unfortunately, the CMOS clock is not designed to be precisely accurate. It is
designed to be inexpensive.
If your clock is drifting when the power is off, the issue is the 32KHz clock,
or the backup battery; if you are drifting when the machine is on, it is the
14.318MHz clock.
You could try replacing these crystals or oscillators on your motherboard,
but the risk of damaging something is high, and the chance it would have a
better result is iffy.
Alas, the internet sync idea is the most practical solution for the vast
majority of users.
 
If connecting to the internet is a problem, perhaps a different connection to
an accurate clock would work?
http://www.timetools.co.uk/atomic-clock/gps-clock.htm supplies a GPS based
time clock correction. This is rated to 100nSec/day!
I believe there are also radio receivers that can connect to the WWV
shortwave radio broadcast timesource.
I am assuming you need this for some sort of laboratory-grade measument.
LynnBr2
 
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