I'm using the Ubuntu kernel PPA's 3.12-rc2 kernel which according to the
changelog has this patch but am still having the problem.  My laptop is
A10-4600M with 7730M discrete GPU.  If I disable gdm and X, I can boot up, log
in to a text mode terminal and do text mode things just fine and dmesg shows
that dpm is enabled for both GPU's, but trying to start X crashes the entire
machine instantly.  This happens when my laptop is plugged in and fully
charged, haven't tested it unplugged and on battery.