|"Might be the cmos battery"|
If the cmos battery is too weak or dead, or is installed backwards or has a poor connection, if nothing is wrong with the power supply or the mboard, you always get a message every time you boot "Cmos Checksum error" or similar.
Are you seeing that?
If you aren't that's probably NOT what is causing your problem!
I mentioned the bad capacitors possibilty because I have personally replaced two mboards of about the same age as yours that had that problem.
The bios has two components
- the cmos part has changable data and retains the current time and date and any other custom settings the computer user makes - the battery is required to retain those settings when the mboard has no power to it.
- the read-only part contains the data that allows the mboard hardware to communicate with the operating system you are using - that data is mostly invisible to the user and can only be changed by flashing the bios - it does not need the battery to retain the data in it.
The battery is usually shaped like a coin, and it's usually in a socket that's flat on the mboard . The + polarity is marked on the battery and that side must be upwards. Unplug the case or switch off the AC the power to the case before you remove it and keep the AC power removed until you have replaced it or have installed a new one in it's socket.
Cmos batteries typically last about 5 years. Since you have a PIII cpu, that indicates your mboard is probably at least 8 years old, and your battery may be too weak or dead if it has never been replaced, or if it hasn't been replaced for along time.
When you remove the battery, wait, then replace it, you
you always get a message "Cmos Checksum error" or similar.
You have to set at least the date and time in the bios Setup - otherwise you will get the same message when you boot the next time.
If the battery is okay, is installed the right way, and has a good connection, you will NOT get the message "Cmos Checksum error" or similar when you boot after that.
If the battery is NOT okay, the bios will retain the time and date and any other custom settings while you continue to use the computer, but when the computer is shut down , then booted, you get a message "Cmos Checksum error" or similar again, because the cmos is unable to retain the custom settings.
Even if the battery is too weak or dead, the bios defaults should still recognize at least whatever drive is connected to the Primary IDE header as master, because the bios defaults would have at least that one drive connection detection enabled by default, if not all of them.
If you tell us the make and model of the mboard, we can probably find the manual for it, and in that manual there is usually info about the bios settings and often what they are set to by default.
The mboard model is frequently printed in larger characters between the slots. If you see a Rev or R or Ver or V number, supply that too - that may be beside the model number, or elsewhere on the mboard in larger characters.
If there is no obvious model number on the mboard, then we need the bios string.
The bios string is usually a long string of numbers/letters at the bottom of the first black screen as you boot your computer - it often begins with a date - usually you can press the Pause key to freeze the display at that point, read it, and copy it down.
Press any key but Pause to continue booting.
It could also be higher up the screen under or beside the bios version line, e.g. under or beside Award or AMI or Pheonix...
Supply the bios string to us, and include any dashes, etc.
Please make sure you copied it right. Most Award and AMI Bios strings do not have spaces. Newer Phoenix bios strings, based most often on those for Intel mboards, are often like so: xxxxxxxx.xxx.xxxxxxxxx