Hello! You said "the south bridge and north bridge chips are hot even if they are not powered on"?
Did you just shut it down or did you turn off the power supply?
It is normal if there is still residual heat after the machine has just been shut down; it is not normal if it is still hot after you have turned off the power of the host. Maybe someone happened to have used your computer not long ago, and you didn't know it, but it was residual heat;
Or maybe your computer is on, but in screen saver or hibernation mode, without turning off the host computer. It will also get hot.
It is recommended that you turn off the host and unplug the power supply. If it still generates heat, congratulations on discovering a new energy source. Apply for a patent quickly! hehe. . . . .