1. Check the three major working conditions of the CPU

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2. Remove the BIOS and check if the 22-pin chip select signal has jumped

3. Try changing the BIOS and check the line connected to the BIOS

4. Check ISA, PCI data lines, address lines (and AD), interrupts and other control lines (this can directly reflect the North-South bridge problem)

5. Check the ground resistance of AGP, PCI and CPU block to judge whether the north bridge is normal

(1) Power supply CPU core voltage

(1) No voltage

A, FET is broken, open circuit or short circuit
B, filter capacitor short circuit (electrolytic capacitor)
C, voltage IC, no output, no 12V power supply

(2) Low voltage
A, CPU working voltage related circuit has a slight short circuit
B, a field effect tube is broken, the output voltage will also become lower
(3) High voltage
C, the feedback circuit has no effect
D, voltage IC output voltage is low

(2) VID0－4 (+5V voltage)

The voltage IC has no output. The resistor connected to the CPU socket is broken.

(3) VTT 1.5V

(1) No voltage
The power supply FET is broken
VTT1.5V has a short circuit to ground
(2) Voltage level
FET power supply is not normal
FET is broken

(4) Clock

(1) No clock
Open circuit between CPU socket and clock IC
No output from clock IC
The filter capacitor connected to the output is broken (10 picofarads)
(2) The clock IC has no output
Is the power supply normal 3.3V 2.8V 2.5V
All no output or half of no output
Whether the crystal oscillator starts to vibrate 22 picofarads are broken
(3) No output at all
No power supply, check power supply related lines
(4) Half of no output
IC is broken, half of the power supply is checked abnormal

(5) Reset

(1) 1.5V without reset
A, reset voltage is low: Northbridge is broken
B, there is voltage without reset
North Bridge false welding or North Bridge without reset
The line connected to the North Bridge is disconnected
(2) The north bridge has no reset (see whether PCI, AGP, IDE are normal)
Reset: disconnected from the North Bridge
No reset: check the reset generating circuit