The 'Generic' LE12 image supports Intel/AMD GPUs, the Generic-Legacy image supports nVidia GPUs; although only as far back as the 340.xx driver series. Also note that 340.xx has been dropped from LE13.
Will I have any chance installing an older version?
Let us see the log from latest LE 12 Generic-legacy first.
I have to ask how I can find the log..
We prefer to get a copy on our log server, which saves storage space here. If you have SSH access, you can activate log level 1 by creating an advancedsettings.xml. Then reboot, run pastekodi from SSH, and post the resulting URL.
There's no point in adding Kodi debug info until Kodi runs, so just do "dmesg | paste" over SSH and share the URL generated.
i am a total beginner so i will need a "instruction for dummies" help 
: ssh, dmesg?
Look for \\LibreELEC\Logfiles on the network. When you click into the folder a zip file with logs is generated. Share that.
Or read this: https://wiki.libreelec.tv/support/log-files
this is the MB
https://it.msi.com/Motherboard/K8NGM2FID_IL_L/support
and this the onboard graphic:
Thanks for your reply.
I guess I have to check the onboard Nvidia chip..
Will I have any chance installing an older version?
NVIDIA GeForce 6100/6150 + nForce 430/410 System Drivers
The last LE release that will support a GeForce 6100 GPU (released in 2004) is LE 7.0.3 from 2016 when the project was new. This is still available in the project archive, but it won't be much use for anything except local file playback today, as anything that talks to the internet will have issues with expired SSL/TLS certificate chains and outdated Kodi add-ons.
So the error message is 100% correct .. GPU is not supported. On hardware that old it's not worth swappiing the GPU for something newer unless you have cards kicking around. If you don't, better to save pennies towards something like a Raspberry Pi board or a small form-factor Intel box.
The GeForce 8600GT should be supported by the 340.xx driver in the LE12 Generic-Legacy image, but drivers are always a bit of a lottery on really old and low-mid range hardware as functional testing always focusses on high-end cards with more features.
giaguaro Did you disable the on board graphic card in the BIOS after adding the 8600GT?
