i'm new on superuser so correct me if i'm breaking some rules here,

I have built a new pc system. when trying to boot both cpu and psu fan spin for a couple secods then go off, and i can re-do this without any need to remove power or anything. if started only connecting the 20+4 pin power cable without the 4 pin cable, the fans spin for more but still i get shut down around 5 seconds. In that brief powering sequence i do get lights on. the setup is core i3 8100 processor, paired with a H110 asus motherboard, using an 8 Gb DDR4 ram. i'm using my previous PSU which i believe is working fine. i don't have any other cards or peripheral connected yet.

My first guesses are either motherboard-CPU incompatibility, or a damaged PSU or motherboard, but i would appreciate any further insights.

UPDATE: i removed the CMOS battery and unplugged the power, after re-plugging the device i get a constant spinning of both CPU and PSU fans, but no other output, not even a beep, and as i try to connect the 4-pin cable, it goes back to previous state, not getting a constant fan spin.

Thanks for any ideas, Have fun in quarantine

  • 1
    I am not too sure what are you referring to when you say 4 Pin PCI Cable. Are you referring to the 4 Pin EPS Power Connector that generally plugs in to the socket besides the CPU? If, so that is required for CPU to receive power, without that connected, system will not boot. PC that powers on but shuts down within seconds could possibly mean (one among other possibilities) is that there's a short somewhere. So the OCP (Over Current Protection) in the PSU is coming into effect and causing the system to shut down. – patkim May 9 at 16:10
  • Thanks, yeah i meant the 4 pin output, which i wrongly thought was for the PCI. Thanks, I'll edit the question. – Hamed Temsah May 9 at 17:18
  • 1
    Somehow I am still not very clear. Is your 4 Pin referring to the 4 Pin out of 20+4 ATX Power Connector? Because apart from that 4 Pin there's also an EPS connector which is also 4 Pin (On High end boards it could even be 4+4) that needs to be plugged into CPU Power socket which is separate from 20+4. If you are making all power connections correctly and still you are getting this behavior, try running the system out of the cabinet. That will rule out any possible issues related to board shorting with chassis somewhere by chance. – patkim May 9 at 19:17
  • Yeah. thanks, did it., i guess it is the CPU-MoBo incompatibility. gonna try with another board soon. Thanks – Hamed Temsah May 10 at 16:12

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