Question House breaker tripping when a new USB device is connected while the computer is completely turned off and then turned back on.

[Athsara]

So today i built a PC , When the computer is powered on normally without any USB connected the computer turns on and works , but when u turn the system completely off (from the psu and pull the cable out) and then connect a USB device from the rear and the turn the PSU switch on the House breaker will trip , but once u turn the switch off , turn the trip back on and then turn the PSU switch on without removing the attached USB then it will turn on normally , this doesnt happen consistently but happens from time to when a New USB is introduced while the power is cut off and the PSU is turned off and then power is given back from the PSU.



What could be the issue?

 

[MoroMoro]

Im no electrician, but that sounds like a problem with resistance.

 

[Athsara]

Im no electrician, but that sounds like a problem with resistance.

are u suggesting that it cud be an issue with the PSU?

 

[mmp09]

If I correctly understand, you just turn on the PSU switch. Not the Power ON Switch or button on the cabinet.

So the PSU when switched on from mains enters a Stand-By state, where it supplies minimum voltage and current required to run certain systems like LAN, RTC etc etc. Only after you press the PowerOn button on cabinet, then full voltage is supplied and system boots.

So try the same config without any cabinet and re-test with min parts. What are the USB devices in question? Does it happen with USB Keyboard/Mouse?

Some shorting somewhere is likely the cause and looks like it's strong enough to override the Over Current Protection deployed in ATX PSU.