BIOS ROM checksum error + incompatible BIOS size on motherboard page (MSI 865GM2 v1.0)

[Lazyad07]

Hey all, I have an 865GM2 v1.0 which randomly went into a BIOS ROM checksum error after plugging in an IDE HDD after fully unplugging the motherboard's power. I have unplugged the drive, taken out the CMOS battery in an attempt to clear the error, yet I am met with the same screen. Additionally, the BIOS chip on this board is an SST 49L002A, which from what I've read can only hold up to a 256KB BIOS ROM. The official page for this motherboard only has 512KB BIOS ROMs which aren't any use to me unfortunately if I do need to end up flashing a new BIOS onto this board (unless there is a workaround I haven't heard of, in which I pray).

I have attached some images for reference, in which the one of the BIOS properly POSTing was before plugging in the hard disk.

Many thanks!

 

[Lazyad07]

UPDATE: I finally managed to fix this board, turns out it isn't a 865GM2, but in fact a 865PEM2 which means different north bridge chipset and a different bios rom. I wish I caught onto this earlier after buying a true 865GM2 motherboard which had VGA out on the board instead of another serial port... As for what caused the checksum error, still no idea. I have this computer up and running now with plenty of backups just in case!

To add on, I didn't switch to the true 865GM2 since most of the capacitors were faulty, I only used it to see what the exact specifications were that could help while it was still kicking.