ZOTAC: CMOS Checksum Bad

zotac.com forum
Did you REALLY clear the CMOS?
1. Pull the power cord out the back.
2. Pull EVERYTHING off the motherboard including internal usb headers, RAM and all power cables so all your left with is the motherboard with attached processor.
3 Pull All Power Cables so absolutely nothing is attached to the power supply
2. Remove CMOS battery.
3. Clear CMOS with Jumper
4. Let Computer sit overnight just to be absolutely sure any capacitors are discharged.
5. Replace CMOS battery
6. Replace CMOS jumoer.
7. Replace RAM and attach power cables to motherboard. Nothing else should be plugged in or attached to the power supply at this point.
8. Attach known working keyboard. (I've had trouble booting previously because my wireless keyboard was running out of batteries)
9. Plug power cord back in press power
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How-to POST Test a Motherboard - POWER ON SELF TEST Guide

• How to Bench Test Your System
  
• PCI PC Diagnostic Card

Recovery method for errors in the BIOS update
If the system doesn't power on and there is no display.
1) Download BIOS.
2) Copy file to USB Flash drive and rename to AMIBOOT.ROM
3) Connect USB Flash drive to USB port.
4) Power on system, press keyboard keys CTRL + HOME and continue to hold keys for 10-15 seconds.
5) When the USB Flash drive LED flash release keys.
6) Wait few minutes and the system will shutdown.
7) The system will turn on and function normally.
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You can flash the BIOS by using AFUDOS. Here are some steps on how to set it up.
* Use this utility to download FreeDOS and install onto USB drive.
* Copy AFUDOS and the BIOS to the USB drive
* Restart
* Load FreeDOS LiveCD with HiMEM + EMM386
* Change drive to B:\
* Flash the BIOS
Make sure you look at the Readme.txt for the AFUDOS command line. Copy exactly what is in the Readme file. 
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zotacusa.com/downloads/?cat=124
http://www.computerbase.de/forum/showthread.php?t=745029

Program all Blocks
Destroy CMOS checksum

hab mit afuwin laut zotac homepage mein Bios auf die neueste Version geflasht und vergessen Destroy CMOS Checksum anzuhacken.

Wenn ich jetzt boote schreibt er mir: CMOS Checksum Bad

Soweit so gut, ich hab dann auf F1 ins Setup - Alles auf Default gesetzt und neu gebootet.

Dann hab ich versucht mittels Jumper nen Cmos Reset zu machen. (Umgejumpert, gewartet, zurück gejumpert...noch immer das selbe Problem.

Dann habe ich die Batterie entfernt und ne Zeit lang gewartet...nach dem Wiedereinsetzten meinte er zwar das Uhrzeit/Datum nichtmehr stimmen und ich die einstellen müsste, aber danach wieder der CMOS Checksum Bad Fehler.

Hab dann versucht mit nem bootfähigem USB Stick mittels Afudos nochmal neu zu flashen, das Problem ist nur der USB Stick wird nicht als Bootable Device gefunden (es gibt kein Write Protection im Bios, dass konnte ich mal ausschließen). Mir ist aufgefallen, dass ich ja trotz änderungen im BIOS und mittels F10 speichern und verlassen trotzdem immer wieder die alten Settings geladen werden...

Stick wurde mittels http://www.biosflash.com/bios-boot-usb-stick.htm#Update erstellt

Possible solutions

Probieren mit 

http://www.biosflash.com/bios-boot-cd.htm

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This problem arises when the step to load the default BIOS settings after the flash is not taken. To fix the issue load the default settings in BIOS and perform a reboot. If the problem persists, attempt a re-flash or CMOS reset and then load the default settings and reboot.

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Reflash the BIOS. I had this issue when I did the upgrade because the default check box for BIOS Image apparently doesn't flash the full BIOS update to the chip. I tried it a second time and checked all the boxes and everything worked great.

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Use AFUDOS vs. AFUWIN (at least it seemed easiest and worked for me).

Make a DOS bootable USB flash drive and copy AFUDOS.exe and the appropriate .rom file to the flash drive.

After booting to the flash drive, you can use the command line:

AFUDOS xxxxxx.rom /B /P /N /X /C

Where xxxx is your boards .rom file name.

The next re-boot should indicate the CMOS checksum is bad, and ask to reset with defaults. Go ahead and do so.

If the next boot does not start without some sort of checksum error, I expect you have a hardware problem.

Also make sure you did not accidentally leave the CMOS reset jumper in the reset position.

To explain a little from the information I got from your post, there are two seperate issues you are dealing with here.

First is your version of ROM BIOS, which is flashed into a flash memory device somewhere in the motherboard electronics.

The functionality of the BIOS is configured using CMOS memory. I gather that you are able to go into the BIOS and change things (like boot order to boot from the flah drive). If this is true, at least part of your BIOS been re-flashed OK, but you are still getting CMOS checksum errors. While I was re-flashing I also noticed there was something called NVRAM being cleared, which may also be part of your checksum error. 

The organization of CMOS/NVRAM could change from version to version of the BIOS. This could change the checksum validly, so it sounds like you have changes the BIOS, and not the CMOS/NVRAM versions.

The command line options have something to do with the resetting the CMOS, NVRAM and other re-flashing options.

You can determine the meaning of each by typing AFUDOS /? after booting from the flah drive and read the options. I got the options directly from the readme file in the .zip file from Zotac.

Anyway, I would not worry about the memory issue until you get the CMOS reset and working properly. This shows 960M memory size shows up in a number of posts, and is apparently also assoiciated with CMOS memory. Once you get the checksum... fixed this should go away and show the memory correctly again.