wrong date & time

[texasgirl]

I have a HP Media Center PC with Windows XP Home Edition. I turned off my
computer and when I turned it back on the date and time were wrong. It had
gone back to 01-06. I corrected the time and date, turned it off then back on
and it had gone back to 12-05. I corrected the date and time again. It
doesn't do this when the computer is restarted. The programs and things are
changed also, I think to what was on the computer at those times. We rarely
turn the computer off, we usually just sign off and the computer is off line
but connected to the internet. We have DSL. We have McAfee Virus and firewall
programs that are always updated.
I ran a thorough virus scan and a malware scan, nothing was found. Scans are
set to automatically run 4 days a week. Any idea what the problem could be?

 

[VanguardLH]

I have a HP Media Center PC with Windows XP Home Edition. I turned off my
computer and when I turned it back on the date and time were wrong. It had
gone back to 01-06. I corrected the time and date, turned it off then back on
and it had gone back to 12-05. I corrected the date and time again. It
doesn't do this when the computer is restarted. The programs and things are
changed also, I think to what was on the computer at those times. We rarely
turn the computer off, we usually just sign off and the computer is off line
but connected to the internet. We have DSL. We have McAfee Virus and firewall
programs that are always updated.
I ran a thorough virus scan and a malware scan, nothing was found. Scans are
set to automatically run 4 days a week. Any idea what the problem could be?

Restarting your computer never removes the power. Turning it off
presumably means you are removing power. When power is removed, a coin
cell (wafer battery) keeps alive the CMOS copy of the BIOS settings
along with providing the power to the RTC (real-time chip) used to track
time. The RTC is used to keep track of time when the computer is
powered off. Once Windows is loaded, the RTC is no longer used and
instead the OS keeps track of time (and why the system time can get
off).

Wafter batteries, when new, have a useful life of 5 years. Even if you
buy a new motherboard or computer, you don't know how long it was from
when the battery was manufactured, in storage, when it was put into the
motherboard, how long that mobo was in storage, how long it sat at the
store, and so on. Either read the manual to find out what battery is
used on the motherboard or open it up and look (probably a CR-2032). Go
buy a new one at Best Buy, Target, Walmart, Radio Shack, or wherever and
replace the old one on your motherboard.

 

[Rey Santos]

It could a weak/dead CMOS battery. Another indication of this is a CMOS
checksum error at start.

"It doesn't do this when the computer is restarted."
When the computer runs the battery starts to recharge and keeps that charge
for a while.

 

[Paul]

It could a weak/dead CMOS battery. Another indication of this is a CMOS
checksum error at start.

"It doesn't do this when the computer is restarted."
When the computer runs the battery starts to recharge and keeps that charge
for a while.

The battery doesn't charge. It does that, because there are
two power sources. Using diode ORing, one power source or
the other is used. The coin cell would not drain, if the
+5VSB was always available (and it is available if you
use S3 suspend to RAM, otherwise known as "sleep").

+5VSB ---- regulator ---- 3VSB ---------- diode ->-+
|
+---> CMOS_well_on_Southbridge
| (clock and CMOS RAM for
CR2032_Coin_Cell --- 1K_ohm_resistor ---- diode ->-+ BIOS settings)

When you reboot the computer, the +5VSB power was running the
whole time. That means the CMOS was receiving power via
the upper leg of the circuit. The clock time would be
retained during the reboot.

When you switch off the computer at the back, or use another
means to remove AC power from the back of the computer, then
the upper leg of the circuit is dead. Then, it is up to the
CR2032 to power the circuit. If the battery is dead (below
about 2.4V), there is insufficient voltage to maintain
the CMOS RAM storage locations, or perhaps, run the clock.

The two diodes shown in the diagram, are unidirectional.
Current can only flow from left to right. The Coin Cell
is never charged (more than 1 microamp of reverse current,
can cause the battery to burst). The Coin Cell has enough energy,
to run the clock for about three years on its own, if the
computer is never plugged in. The coin cell will last longer
than that, if the computer standby power (+5VSB) runs for an
appreciable percentage of the day.

In some cases, a bad battery can even prevent the computer
from starting. But if that happens, chances are a different
circuit configuration than the one shown above, is being
used.

Paul

 

[Singapore Computer Service]

Hello,

As the rest have said, you need to change the CMOS battery. Google -
http://www.google.com/search?q=change+cmos+battery - has plenty of
references to such guides, or you can bring down your desktop to your
nearest qualified computer repair shop and have them replace the battery for
you if you are not comfortable with opening up the desktop.

Regards,
Singapore Computer Home Repair Service
http://www.bootstrike.com/ComputerService/
Video Conversion VHS Video8 Hi8 Digital8 MiniDv MicroMv
http://www.bootstrike.com/VHSVideoConvert/

 

[Ken Blake, MVP]

I have a HP Media Center PC with Windows XP Home Edition. I turned off my
computer and when I turned it back on the date and time were wrong. It had
gone back to 01-06.

Almost certainly, your motherboard battery needs to be replaced. It's
a flat disk on the motherboard about the size and shape of a US
quarter, and can be replaced for around $3.

I corrected the time and date, turned it off then back on
and it had gone back to 12-05. I corrected the date and time again. It
doesn't do this when the computer is restarted.

No, because restarting doesn't remove power from the battery. Turning
it off does.

 

[VanguardLH]

Hello,
...
Regards,
Singapore Computer Home Repair Service
http://www.bootstrike.com/ComputerService/
Video Conversion VHS Video8 Hi8 Digital8 MiniDv MicroMv
http://www.bootstrike.com/VHSVideoConvert/

Be leery of advice from a SPAMMER who has a different agenda than the
pretense of giving help. This one does knows how to put his spam in a
signature but refuses to do so because some newsreaders strip off the
signature. He wants to ensure you see his spam.