commonly, CPU_RST# has a pull-up resistor connection to

commonly, CPU_RST# has a pull-up resistor connection to +GMCH_VTT, and is connected to corresponding pins of CPU socket on one side and north bridgge on the other. Did you check NB powers are Ok? Give, please, a measured resistance values from CPU_RST (pin "G23" at LGA 775) to ground and to GMCH_VTT output