Gigabyte GA-G31M-ES2L with BIOS error

[Chungalin]

Not a caps problem, but interesting and freaky repair anyway...

This MB does POST fine but before booting (or before trying to enter Setup) it shows an error message:

Warning: MAIN BIOS CHECKSUM ERROR!

Then it says it'll try to restore Main BIOS from Backup BIOS, but no progress is shown and it stays this way forever.

This MB is DualBIOS. It has two Flash ICs to store BIOS, Main ("M_BIOS") and Backup ("B_BIOS"), both SST (Silicon Storage Technology) SST25VF040B-80-4I-S2AE, in a SOIC-8-Wide package.

First I try to ressolder Main IC, to no avail. Then I dessolder Main IC. It still makes POST and show same error message, but when it wants to restore from backup, it just shuts down computer and restarts. Quite normal if it detects something very wrong when trying to write flash IC. Interesting that it doesn't need Main BIOS at all to make POST!!

Then I pull a SST25LF040A-33-4C-S2AE from scrapped Dell E187242 Connolly, I solder it in place of Main BIOS (no previous erasing, I don't have tools to do this) and let it start... Same POST, same error, BUT now it actually restores Main BIOS from Backup, as it shows a progress dot line. After some seconds it reboots and everything is fine!

Apparently the main difference between original IC and replacement is max clock frequency, but probably MB accesses it much slower than 80 and 33 MHz. Well, it works, and that's all!

[q4midz]

Re: Gigabyte GA-G31M-ES2L with BIOS checksum error

Not a caps problem, but interesting and freaky repair anyway...

This MB does POST fine but before booting (or before trying to enter Setup) it shows an error message:

Warning: MAIN BIOS CHECKSUM ERROR!

Then it says it'll try to restore Main BIOS from Backup BIOS, but no progress is shown and it stays this way forever.

This MB is DualBIOS. It has two Flash ICs to store BIOS, Main ("M_BIOS") and Backup ("B_BIOS"), both SST (Silicon Storage Technology) SST25VF040B-80-4I-S2AE, in a SOIC-8-Wide package.

First I try to ressolder Main IC, to no avail. Then I dessolder Main IC. It still makes POST and show same error message, but when it wants to restore from backup, it just shuts down computer and restarts. Quite normal if it detects something very wrong when trying to write flash IC. Interesting that it doesn't need Main BIOS at all to make POST!!

Then I pull a SST25LF040A-33-4C-S2AE from scrapped Dell E187242 Connolly, I solder it in place of Main BIOS (no previous erasing, I don't have tools to do this) and let it start... Same POST, same error, BUT now it actually restores Main BIOS from Backup, as it shows a progress dot line. After some seconds it reboots and everything is fine!

Apparently the main difference between original IC and replacement is max clock frequency, but probably MB accesses it much slower than 80 and 33 MHz. Well, it works, and that's all!

thank you,i replace main bios 25L40 with MX25L80 from samsungtv mainboard and problem solved