In grub, remove quiet and splash from kernel parameters. See what is the last message on the screen.
Also try to boot from LiveCD.
Hi, All
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
In grub, remove quiet and splash from kernel parameters. See what is the last message on the screen.
Also try to boot from LiveCD.
Maybe you need a bios update.
Does it make a difference if you boot with radeon.modeset=0 kernel parameter? Can you also try Ubuntu 12.04 beta?
If w7 boots on same cpu, mb is fine.
Try to switch "C1E" to "OFF" in BIOS.
[QUOTE=Dennis8888;246353]Maybe you need a bios update.[img]
BIOS has been updated to the latest version.