Mystery things do not stop. Now I succeeded when flashing the original BIOS with the patched version as one can see by flashrom's output:
flashrom v0.9.1-r845 (patched) No coreboot table found. Found chipset "AMD SB700/SB710/SB750", enabling flash write... OK. This chipset supports the following protocols: LPC,FWH,SPI. Calibrating delay loop... OK. Found chip "SST SST25VF016B" (2048 KB, SPI) at physical address 0xffe00000. === This flash part has status UNTESTED for operations: ERASE Please email a report to flashrom@flashrom.org if any of the above operations work correctly for you with this flash part. Please include the flashrom output with the additional -V option for all operations you tested (-V, -rV, -wV, -EV), and mention which mainboard or programmer you tested. Thanks for your help! === Flash image seems to be a legacy BIOS. Disabling checks. Writing flash chip... Erasing flash before programming... done. COMPLETE. Verifying flash... VERIFIED.
A verification by reading the BIOS (via flashrom -r <file>) and comparing it with the original bios (via diff) shows the NO difference.
For now I think we can say good night. But I would be very pleased if we fix the problem tomorrow. The original job to flash a new bios isn't done up to now ...
Best,
Parallix