If you haven't already, I would highly recommend submitting an RMA request to replace the motherboard. That is not acceptable for a month-old laptop. Once it's replaced, dial in an undervolt immediately, the voltage will still spike but won't be near...
I don't have a ROG laptop, I have a Lenovo Legion with the 13900HX/4080. I've had the motherboard replaced because of this issue already, 2 months ago. I've only had the laptop since September of 2023, it took 9 months for the CPU to degrade to the p...