View Full Version : CMOS/GPNV error

02-10-2002, 03:47 PM
Most times when I turn my computer on I get a message CMOS/GPNV checksum bad
F1 to fun setup
F2 to load default value and continue.
I press F2 and all runs as normal. How do I get my computer to load properly? I Know enough about computers to wreck things and not enough to fix things.

02-10-2002, 04:00 PM
try a new cmos battery. tho i have seen that on some old boards when the correct/incorrect date is used.

what sort of motherboard does it have?

02-10-2002, 04:02 PM
The first fix (assuming you havent upgraded the system and/or reflashed the BIOS) is to fit a new battery to the motherboard. As you dont give any clue to the computer type/age etc cant be more help.

02-10-2002, 04:02 PM
It could just be a flat CMOS battery.
If it is a Pentium or later the battery is most likely a CR2032 type (Looks like a 10 cent coin) and these can be bought from most appliance stores/jewellers and are pretty easy to change yourself.

Babe Ruth
02-10-2002, 04:11 PM
If the BIOS has been 'flashed' (upgraded) then the CMOS options are reset.
You'll need to go back into CMOS setup and set the options to save it.

If the BIOS has not been flashed then maybe it is the CMOS battery on the motherboard needing replacement.

Now you're going to ask how the heck do I do any of that!

Well it depends on a number of things but essentially you should be able to go into the BIOS when you first boot up the computer by pressing the DEL key.
Without knowing your particular BIOS (the name something like AMIBIOS or Phoenix) I won't say.
Post back all the details of your machine (that you know) and we'll see if we can help.

As far as the battery goes if your pc is under warrenty then take it back to the shop and tell them to fix it. Same thing applies for setting the BIOS / CMOS.
if not under warrenty and you're not keen on doing the job your self find a knowledgeable person to help you through this. The batteries are only a couple of dollars from a supermarket.


Graham L
02-10-2002, 05:40 PM
The checksum error is calculated on the values which are saved in the CMOS memory. It does not include the date or time values. Iyt is checked as part of the power up testing.

So a checksum error means that while the computer is turned off, the battery was too low to keep the saved values. The clock will probably have stopped or gone erratic during that time too so the OS will have wrong date/time when it starts.

That F2] response loads the default values for the BIOS, and saves them. That fixes the checksum ... because that is calculated when the settings are saved.

The repair is to replace the battery. There are "four" sorts of battery.
(1) a 3-button NiCd soldered to the board (This sort is on "older" machines. (About 20 mm diameter and about 30 mm long --- often in a blue heatshrink tube). Not easily replaceable (you need a soldering iron and to know what you're doing)
(2) a plugged in Lithium pack (a rectangular box about the size of a matchbox -- usually black, and mounted on a velcro pad). Easily replaceable, but expensive (I'd replace one of these with a battery container and 4 AA alkalines).
(3) a "coin" lithium about the size of a shilling (10c to you young uns). This is in a flat clip holder on the motherboard. This is easy to change.
(4) some computers have a (usually) Dallas package which contains the bios/cmos and the battery all in one unit. If it's that sort, you pretty well have to live with the problem.
(5) some IBMs used lithium batteries like those used in cameras, but with soldered on leads ... replaceable with some tricks. [This is why I quoted 'four' at the start .. I knew I'd think of something ;-)]

03-10-2002, 12:49 PM
Thank you for your help

03-10-2002, 12:51 PM
Thank you for your help

31-01-2006, 12:33 AM
Every time i turn on my pc, this one comes out

Legacy keyboard.....detected
Legacy mouse.........detected

CMOS/GPNV Checksum Bad
press F4 to enter setup

What does it mean?

31-01-2006, 12:57 AM
It means the setup information held in the CMOS (Non-Volatile) RAM has changed.

As indicated in the 2+ year old post that you have added to above, it usually indicates that you need to replace the battery on the motherboard. Its usually a CR2032 lithium cell, the size of a small coin and silver, held by a clip. Just be gentle unclipping it so you don't break the clip when replacing it.