Firstly, when we press the power button the SMPS and CPU fan spins and then stops repeatedly. This problem is due to an incomplete power rail. In the motherboard voltages turn on one after another is called a Sequence.
If one of the voltages gives some problem then the cycle is not able to complete. Then the CPU fan spins then the stops repeatedly problem occurs.
How to solve CPU fan spins then stops repeatedly
Following are steps to solve this problem of CPU fan spins then stops repeatedly :
Replace SMPS and recheck
The first thing to do is to change the SMPS and check with another SMPS. The problem might be SMPS.
Check any short circuits in the motherboard
Check for any short circuits that occurred in the motherboard. You can check it by doing hot testing and cold testing.
You will also need some tools and information about components to check this.
Check DDR Voltage
Thirdly do check for DDR voltage is coming or not. DIfferent DDR RAM has different DDR voltages. If it’s not coming to the check RAM Buck Converter power or if it’s coming then proceed to the next step.
1.05 Voltage Is Coming
Check whether a 1.05 voltage is generated or not. If it is not getting generated check for a 1.05V buck convertor. Else proceed to the next step.
VTT Voltage Is Ok
Firstly check whether VTT voltage is coming or not. If VTT voltage is not coming then check VTT buck convertor power, else go to the next step.
CPU Core Voltage Is Coming?
Check whether CPU core voltage is coming or not. If it is coming then go to the next step else check whether 12V is shorting.
If it’s not shoring then check the VR ON signal and 5V VCC supply. Secondly, If VR ON and VCC are coming then do replace the VRM chip and VRM MOSFET.
Check VRM PWRGD Signal Coming
If it’s coming then go to the next step.
Is SYS_PWROK Signal Is Going To SIO
If the SYS_PWROK signal is going then go to the next step.
Heat PCH And Recheck
Finally, if everything else fails heat the PCH using the SMD station and recheck. It should be working properly.
You can also check for other desktop repairing information such as a desktop motherboard repair guide, power supply for check for the dead desktop motherboard, and desktop SMPS output information.
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