cmos problem

this has been bugging me for a long time and now i have seen it two more times this week.

this has been happening to my machine for quite some time but have learned to live with it by just not unplugging my machines power cord fromt the psu. what happens tho if i do unplug it is that i loose my cmos settings. i know what your going to say just change the battery on the board but that aint the problem. have done that with brand new batteries and still a problem but like i say i have just learned not to unplug the power cord. now tho i have had this on 2 other machines this week and again changing the battery does nothing to fix it. keep the power cord plugged in and no problem shutting machine down and bringing back up.

any idea ???

 

steve r jones

closer to 5 in all cases. so based on what your saying this could be why in mine and the others cuz i havent seen it with the new dells or newer machines i work on just the older ones. well now at least i know.

thanks man.

 

Something to check on older systems is a jumper that was used to reset the bios or to disconnect the battery.

 

Actually, these jumpers are on almost all motherboards - a few of the latest mid-to-high end motherboards have reset buttons on the rear I/O panel - nice! But to Paul's point, this jumper is used to short two pins on the motherboard momentarily. This action, removes the voltage on the CMOS, it dumps the data stored within, resetting the BIOS. If this jumper is left in the reset position, it may be causing your problem.

Look in your manual, or check the motherboard or PC maker's site for the latest manual to download. There should be an illustration showing you the location and proper setting of the jumper for normal operation and reset. You will need to carefully inspect the motherboard to ensure you have the correct pair of pins. To get the latest from the download site, you will need the exact make and model number of the motherboard or PC.

The deal with keeping the power cord plugged in is due to ATX Form Factor standards requiring all ATX power supplies supply +5Vsb standby voltage across several points on the motherboard. This is for such things as Wake on LAN, Wake on Modem, and the front panel power switch. It also supplies that +5Vsb power to the CMOS memory module. This is true as long as the power cord is plugged in, and the master power switch on the back of the power supply (if equipped) is set to 'on'.

When power is completely removed via the cord or master power switch, the battery is suppose to take over. So, if your jumper has been left in the reset position, when power is removed, the CMOS gets reset every time.