I have the same problems with my intel 5520 chipset based motheboard, the fix for me is install ubuntu with acpic off, installing microcode packages (microcode.ctl & intel-microcode), restart and turn on back acpic on bios, in my side it works now.
I have the same problems with my intel 5520 chipset based motheboard, the fix for me is install ubuntu with acpic off, installing microcode packages (microcode.ctl & intel-microcode), restart and turn on back acpic on bios, in my side it works now.