Motherboard send electricity to case!?

[eyezpy]

Hi,

I visting my parents in Taiwan and just put together a PC using a MSI 880GM-E41 motherboard the other day for them and found that the PC did not like a cold boot (mains off to power on).
Everything will power up but no screen. The num lock works and can be swithched on and off, but no hdd light and system can not be shut down using power putton, only by switching the PSU off.

In order for the system to go into Windows I had to re-plug the connectors on the cases to the motherboard while the main and the PSU is powered (the sytem is not running but power is going through).

If I run my finger over the case (Silverstone SG03) it feels like it is vibrating, but I think it actually is some current going through the case from the motherboard. Also touching the pins (eg USB) on the motherboard I feel slight numbness on my finger tips.

Now does this mean the motherboard have bad wiring and should be return immediately, or should I just get some washers for the mouting wholes? or would it be something else like bad PSU?

[PC4Free]

Did you install the motherboard stand-offs?

[eyezpy]

The stand off are soldered to the motherboard tray which is part of the case.

[Legthigh]

Build it out of case to eliminate it being a short, then you can start to look elsewhere.

[eyezpy]

Have taken the motherboard out of the case and it seem to cold boot a couple of times into Windows fine.

[Legthigh]

Sounds like it's shorting on the case then

You could try fitting the motherboard back into the case (don't screw it in place yet) and seeing if it still works, if it does, fit one screw at a time and re-test after each one until it doesn't work, then you'll have a good idea what is causing the short.

Also try it with and without the I/O Shield and also make sure none of the standoffs are touching the board where they shouldn't be.

[eyezpy]

Thanks for the advice I was just thinking of puting the motherboard in without screwing it in. Screwing one at a time and I/O wouls narrow to which part is causing the short, unless it was shorting underneath or all of the mouting whole are shorting... @,@

Either way it looks like the motherboard is shorting right? If so does that mean its faulty?

[Legthigh]

Thanks for the advice I was just thinking of puting the motherboard in without screwing it in. Screwing one at a time and I/O wouls narrow to which part is causing the short, unless it was shorting underneath or all of the mouting whole are shorting... @,@

Either way it looks like the motherboard is shorting right? If so does that mean its faulty?

Nah the motherboard should be fine, what case are you using?

Usually it's down to a cheap or badly designed case, or just a bit of metal where it shouldn't be.

[eyezpy]

Silverstone Sugo SG03 case.

So you don't think there could be something wrong with the wiring on the motherboard?

[eyezpy]

After taking out the motherboard out of the case and screwing it back in, the PC seem to be restarting fine now, even from cold boot.

Also some thing that I did not mention in my first post, before I re-fitted the motherboard, the pc would not discharge (discharge as in after you shut down from windows, turn off the PSU and then hold down the power button on the case). Normally if it discharges the system fans and motherboard LED would light up and spin once. It did not do that before, but now it does, at least most of the time I think. Don't know if this means anything?

Another thing I have just found out, which I feel is very wired, but might just be normal and just never notice it before is about when the case feels like it is vibrating as I brush over it with my bare hands/fingers. The vibrating sensation (and sound) happens only when the monitor is powered and is plugged into the system and my feet has to be touching my tile floor!? If I am wearig my flip-flops it won't.

Anyone have an explination or theory on why this happens?
Just to be clear I am not on any medication or should be on any I even got another person to try it to verify the vibration is not in my head.

[peterb]

The tingling you feel from the case is mains leakage - very low current and not dangerous, but it does indicate a problem with the earth bonding somewhere (which could be in the mains wiring in the house.)

You need to check that the PSU is firmly located on the case, and that the mains cable has good earth continuity.

The monitor is probably powered by one of the in line "brick" PSUs and they can be leaky, and that is probably the cause of the problem. Often they have no earth bonding on the input, (is it a two or three pin input plug?) and rely on the fact that they are double insulated for electrical safety. You might be able to alleviate the problem by ensuring that the monitor cable is firmly connected at each end, using any securing screws, to ensure good earth continuity.

To repeat, it is unlikely to be dangerous, but it is disconcerting. If you can't reduce the effect by the methods described above, you may have to purchase a replacement monitor PSU. (I am assuming that you are using a reputable branded PSU in the main PC unit - cheap 'n' nasty computer PSUs can exhibit the same effect, usually attributable to inadequate earth bonding internally, or poorly designed/cheap components on the mains input filter.

[eyezpy]

Yes, very disconcerting in deed. My main concern is that nothing will go wrong when I go back to the UK. It’s a lot harder to fix or trouble shoot from thousands of miles away.

I inspected all the connections again and everything seem to be plugged in properly and now the tingling feeling happens with either just the power supply plugged in or with just the monitor plugged.
Maybe it is like you say to do with the wiring in the building, but the flat is part of a 16 floor complex so probably not much I can do about that.
Hard to believe my Samsung SyncMaster 2232BW could be giving leaking voltages through the VGA cable…
The PSU is not a brand I am familiar with, it’s a simple HES 400W PSU, manufactured on the 6th Oct 2010. The guy that sold it to me told me the brand was not too bad… It is a bit light, but then again it is not a fancy PSU and only 400W.

The plug and multi plug are three pi n, but all the wall sockets in this flat are two pin parallel | |.

[Pob255]

HEC is not a great brand for psu quality, they do basic functional psu's mainly for the OEM market, but they also make some right junk as well, mainly their more fancy looking "gamer" psu's (Xpower and Arctic power)
They generally massively over state the psu's wattage, but they also reduce the number of connectors so it becomes hard to pull the stated wattage from them anyway.

It does sound like something is shorting to the case and it could be the PSU itself
try taking the psu out of the pc case, jump start the psu and then see if you're getting that staticy feeling from the case of the psu.

You could run a separate earth lead from the pc case to correctly ground it.
I don't know enough about how 2pin AC works to help, it does sound like there's some current going through the case, so ether some part of the case is touching exposed wire/pcb causing a short through the case or that psu has a very messy ground and case is picking up the current from the psu.

[eyezpy]

Not sure how the two pin AC works here neither.
Have already tried with PSU out of case, but still tingle.
Have also tried not plugging the power lead into the PSU, which still tingles as long as the monitor is plugged in.

[Pob255]

If you're saying you only get this electrical issue when the monitor is plugged in then it sounds like the monitor is the culprit which is rather worrying.

[eyezpy]

No, I mean it happens as when either PSU or monitor is plugged in or both.