Boot problem

  Elrond 20:33 11 Feb 2003

Earlier I tried to boot and the PC halted at the first startup screen, where it tells you how to access bios etc. There was the following message on the screen.

Display Switch Loaded Incorrectly

CMOS Check Sum error- defaults loaded
CMOS Battery Failed
Override Enabled- defaults loaded

After assuming the CMOS battery had gone I popped out to get a new one. Got back,and before just going ahead and putting it in I thought i'd try the PC again. Surprise, it started up. Odd I thought. Anyways, popped out to cinema and just come back and got the same error. So turned off PC and Checked all cables etc, mades sure CMOS battery was in, plugged up and now everything fine. So, any ideas?

  spikeychris 21:10 11 Feb 2003

Explanation: A checksum is computed as an error-detecting code, to protect the BIOS settings stored in the CMOS memory. Each time the system is booted this number is recomputed and checked against the stored value. If they do not match, an error message is generated to tell you that the CMOS memory contents may have been corrupted and therefore some settings may be wrong. BIOSes react in different ways to encountering this sort of error. Some will warn the user and then continue on with whatever settings were in the CMOS. Others will assume that the settings that were in the CMOS were corrupted and will load default values stored in the BIOS chip "for safety reasons". The error message will indicate which your system is doing.

Diagnosis: The most common cause of checksum errors in CMOS is a battery that is losing power. Viruses can also affect CMOS settings, and motherboard

Yours has loaded the default values stored in the BIOS chip.


  Lone Crow 21:21 11 Feb 2003

If it's the variability that is confusing you, it's because batteries vary in their capacity according to load conditions, temperature, etc., so after leaving it alone for a little while it may have recovered just enough charge to enable a full BIOS boot, but being basically 'flat' it wouldn't last. The new one is obviously what is needed and should end your problems, though you may have to do some tweaking to get the BIOS back as it was before if it has lost its settings and returned to the defaults permanently. LC.

  cream. 22:05 11 Feb 2003

CMOS batteries can be funny things. If you have a very low battery and you shut down and then switch off at the mains plug. You always seem to get loading cmos defaults.

If on the other hand you shut down and leave the power connector still switched on at the mains, it will boot as if the battery is fully charged.

There must be a trickle charge that goes through the system that keeps the cmos intact.

Is this your situation?

  Elrond 09:12 12 Feb 2003

I turned on again this morning and it happened again. I turned off and at the mains and nothing happened. I turned on a few times where i got nothing at all, the monitor didn't respond and i got no bios beep or anything. So turned off computer,leaving it on at the mains, pushed on the battery then turned on and it started up. Do you think I shud just change the battery. A friend of mine laughed at me yesterday wen I suggested this, he said that the batteries shud have about 20years life in them and are charged wen the system is on. So all in all, i seem to have the situation that the village idiot suggested.

  Elrond 09:14 12 Feb 2003

What i can't understand is, i have had this mobo since november and haven't had one problem.

  Stuartli 09:31 12 Feb 2003

It's highly unlikely that a CMOS battery will last 20 years!

Further, if you have only had the mobo for a few months, then take it up with the retailer as the battery should last a long time; years rather than months.

My own mobo is four years old and still has the original CMOS battery.

  BrianW 09:39 12 Feb 2003

I agree with Stuartli - I think you board need checking as it sounds as if there is an intermittent short circuit somewhere on the board, either that or a dry soldered connection.

  Elrond 09:39 12 Feb 2003

To be honest I can't remember where I had the MOBO from, and I can't find the receipt etc either, so that's a bit of a no go. MY PC is pretty essential, so getting onto the retailer which cud event in not having a computer for a few days wud be a bit of a problem. It does sound more like something wrong with the battery though as, further to spikeychris's post, i did a little reading and found that it is usually the battery losing power if you get a checksum error. I think I'll go into CMOS/BIOS and note all settings ready for a battery change.

  Elrond 09:41 12 Feb 2003

As i posted b4 the board has run perfectly well for thelast three months not one problem. Why start now?

  Elrond 13:31 12 Feb 2003

Any further ideas. I have just had a message off the other half that she had to restart the PC and it took a while to get going. I don't get home till 6:30 so can't do anything till then.

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