<< Solved >> Snow Leopard 10.6.8. wont boot

[rotton]

You cannot get the boot:0 error if you boot with Clover so obviously you are not.
You can install it with MultiBeast or the Clover installer.
You can even copy the EFI folder from your USB installer to the EFI partition of your hard drive.

Ok, this seems to be an ASRock-specific problem; fortunately, ctyler's fix worked like a charm and I can boot without USB thumb drive.
Problem now is that network connectivity is gone; it says that no Ethernet card was detected, although onboard Ethernet worked during and right after install! I also installed Realtek RTL8111E kext via Multibeast, but no luck. Probably the last obstacle keeping me from High Sierra... Any suggestions?