Hardware: MB GigaByte GA-870A-USB3 rev3.1 (latest BIOS), CPU AMD Phenome II 925, Video Nvidia GeForce 560GTX.
Soft: Sabayon 7 KDE, Ubuntu 11.10
Everything worked well, then I bought a AMD FX 8120 - not loaded both systems, after GRUB black screen and computer freezes.
Windows 7 x64 works fine.
Sorry for my english, I'm from Russia, and writing through Google Translate