PC won't boot with Ethernet plugged in

[Mugsy]

This is more of an "electrical" problem, but I'm not sure where else to post this.

I just built a new PC for a friend. Everything works fine from my house. But when I delivered the new computer, it refuses to boot as long as the Ethernet cable is plugged in (fans & lights, but that's it. Doesn't even post.) Unplug the Ethernet cable, and everything boots just fine.

His speakers also buzz loudly when anything touches the audio plug (be it the computer or just my finger.)

Both issues suggest a "grounding" issue in his apartment. We tried different cables & different outlets, but nothing helped.

BUT his old PC worked just fine. His new computer works fine at my place (even when using an Ethernet cable), so the problem is NOT the new computer I just built. It's something at his place.

What on Earth (pun intended) could be the problem and how do I fix it? TIA.

 

[MaikuTech]

Like I mentioned in your other thread, we need his full computer specs.
Without that info his problem will remain unless you figure it out by yourself.
If his old pc works fine at your place and his home its not a electrical problem.
The problem may fall back on you (the computer technician) it sounds like a grounding issue inside of his case.

If the mobo isn't correctly placed on the mobo mounting pegs with the right screw drivers.
What your having problems with now is most likely to happen.
Its a common problem for new or novice computer builders but not a fatal one if you fix it quickly.

If the mobo is tightened too much, I **** you not, but that computer will not come on or have faint signs of power while trying to boot up.
If the mobo is on but the screws are little too lose, yes it will come on fully but if you move it just a tad bit.
There goes the computer going back off and doing a repeating or random boot loop.
Samething goes for video cards, sound cards and whatever else.