...you are welcomeThank you very much, I tried installing Catalina and the installation was successful. Big sur probably won't work with my hardware.
...some points could still be adjusted, but I use OpenCore 0.6.8Your .plist is wrong: https://opencore.slowgeek.com/?file=sandybridge066i2FG3q&rs=sandybridge066
I use now 0.6.9 version with the same configuration - it works fine....some points could still be adjusted, but I use OpenCore 0.6.8