I would suggest you first check if your BIOS/Firmware is updated. Also check if the components, especially memory, is on the Tested memory and hardware list.
As for C-states, those are the power saving states to reduce power consumption while the CPU is idle. Deeper C-States means lower power consumption, but longer entry/exit latency. C6 is the deep power down state that the CPU internal voltage is close to 0. You may try to disable it as a step of troubleshooting.