cmos battery discharging

[baiju]

hi, I changed my cmos battery on intel motherboard(9yrs old) which showed an error on start up 'cmos time not set',but after two days computer shows same error.It seems cmos battery have deep discharged.what could be the problem,please help!!

[greenpossum]

What's the voltage of the new cell? Was it a good cell or could it have been already half dead? If the motherboard keeps eating batteries then it may be drawing too much current. Corrosion on the board?

On the other hand, if the cells, both old and new, are good, then you may have a bad CMOS memory chip that fails the check.

[baiju]

battery was brand new 3.3volts,I suspect some problem with motherboard .pc was not working for months.when i opened up and reseated the ram it started working again .then i had the cmos error and inserted a new battery. old battery was dead.No corrosion on mother board.

[greenpossum]

The RAM in question is not the RAM used for computation but rather some low power RAM in the clock chip, or often a combo chip, that stores the time, and some additional config info. This chip is usually soldered in so you can't reseat it. If the chip is faulty, there is not much you can do because it may not be cheap to get a replacement.