AMD A8-6500 + MSI A78M-E35 Very sorry but the machine reboots suddenly, so I cannot dump logs... Even acpi=ht is broken. My machine is fine with 3.12.15.
This is a regression. Please do git bisect between stable tree 3.12.7 and 3.13.7. Here is a guide. http://wiki.gentoo.org/wiki/Kernel_git-bisect
Well, really really sorry. Passing radeon.dpm=0 temporally solves the issue. So this is a potential duplicate for https://bugzilla.kernel.org/show_bug.cgi?id=71891. *** This bug has been marked as a duplicate of bug 71891 ***