Here are my test results:
Tank you for the TIP. I switched Chipset Featuresw -> System BIOS Cacheable to "Disabled" and all works fine now !
I decided to leave the 2.1 I already had in my Flash-BIOS there.
The 2.1 downloaded from Gigabyte was different in some bytes and brought no advantages...
If someone wants to have it just answer to this topic ... I'll come back.
Destroying results of the 2.1+ patched BIOS from WimsBIOS.com !!!
This BIOS always hanged in Standard CMOS Setup and also seemed to be unstable in IDE HDD Auto Detection. Horrible GFX errors and no reaction any more.
The Machine booted up, no problem, but the BIOS had these two errors. So I skipped it.
I hope someone can use this information
Thank you for your support