An Asus P5LDZ SE motherboard said can not trigger the boot, I get the board after the power supply, found that the CPU fan turn to stop, the first reaction CPU power supply department short circuit, unplug the CPU power supply interface, the motherboard can be powered on, the problem is determined to be the CPU power supply short circuit problem! The power supply tube of the CPU power supply part has a short circuit in the upper tube part, the resistance value is only 4, and the lower tube has no short circuit! This board is three-phase power supply, remove 3 groups of tubes, measurement, there is a tube breakdown, find a tube of the same type, install them respectively, test the power supply port, no short circuit, power on 2 seconds, and protective power off! Is there a short circuit at the top of the circuit? ! But just now the pipe changed I measured not short circuit wow!!! So do not give up and measure, it is the tube short, and then remove the three tube, find an identical and then change to go, and then test the power supply port to determine that there is no short circuit, power on again, it is 2 seconds protective power, distressed ah, my field tube! This time, I confirm that there must be damaged or bad components in the upper level. This board is powered by ADP3181+3 ADP3110. Carefully check the surface of these chips without traces of damage! First find the chip for it, find N motherboards did not find the same, found the ADP3418, by looking for information, compare the two chip pin definition is completely consistent! Theories can be replaced! So I began to disassemble ADP3110, put ADP3418 in place, and then completely disassemble the upper tube that had just been burned, and found 06N03LA as the new upper tube to install! The original model of the upper tube is: NIKOS P1703BDG, no information of this tube can be found! Measured this tube is the tube of N channel! In addition: ADP3110 can be replaced with ADP3418!! Connected to the power supply this time, the diagnostic card ran the code happily!!! Write the maintenance process of this board, so that in the future, when someone encounters this failure of this board, they can take less detours!