CMOS Checksum errors

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GroBag
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Joined: Sat Feb 07, 2009 2:22 pm

I have just started getting CMOS Checksum errors - seemingly at random but most normally when the machine is powered down for a few hours. I have replaced the battery and cleaned the connectors but the Checksum errors continue.

Occasionally the PC wont POST - just black screen and I will have to clear CMOS with jumpers before I can POST again.

I have made sure to load default BIOS settings and synchronize BIOS clock with Windows. Scanned the MoBo for bad capacitors - looks fine. PSU is pretty much brand new. Voltage ratings are stable under full load.

Possible causes??? - Not really sure just clutching at straws

Motherboard - connection from CMOS chip to battery disrupted??? Only fix is to clean MB?

CMOS corrupted in some way? - Reflash the BIOS????

Faulty peripheral device causing corruption??? - could a faulty device (e.g. soundcard) be responsible for CMOS checksum errors ?

PC not shutting down correctly??? - I have an external HDD that seems to take longer than PC to power down but I have tried removing that before I shutdown and still get CMOS error.

I switched to water-cooling about 2 weeks ago. CMOS errors started about a week after the WC was installed. The system runs stable on Prime95, AtITool, 3DMark etc...Seems rock solid other than CMOS erros.

Asus A8N-VM - thinking of replacing but still would like to figure out these CMOS problems
AMD64 4000+
1 GB Geil Ultra
ATI X1900 GT
SB Audigy
36Gb Raptor x2
750GB Maxtor USB
480W PSU
Win XP Pro SP3

Any ideas/suggestions welcome. I think I will try re-flashing the BIOS and report back here with any findings.
Denniss
BIOS Guru
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Location: Near Hannover (CEBIT) Germany
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The water cooling may be a cause of the problem if the behaviour started just one week later and if you're sure you really properly replaced the battery (some new ones may be old/dead - did you check the voltage of your old and new batts?) and the connection in the battery socket is OK.

It may be possible some parts of the motherboards are overheating as areas especially around the CPU (voltage regulators, chipset cooler) are designed to be in the CPU cooler airflow to get some cooling.
edwin
The Hardware Archivist
Posts: 6286
Joined: Wed Mar 20, 2002 7:11 pm
Location: Netherlands
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this board may be suffering from bad capacitors, please check:
http://www.badcaps.net
edwin/evasive

Do not assume anything

System error, strike any user to continue...
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