Isolate ground for motherboard from required?

[tempoct]

Hi,
Do you isolate the ground of motherboard from the case? (usually by using insulated washers when mounting the mobo). I usually don't do it, but is it really needed?

I talk to a guy today and he said it is absolutely better to isolate the ground of mobo from the case. I don't see much the point since even we use insulated washers, when mounting other components, says graphic card, the ground of graphic card will touch the case anyway. So, what's the different?

Anyone know?
:disgust:

 

[bruceb]

The only thing you need to check is Where on the Mobo the Spacers will be mounted ... if there is plenty of room around the Spacer
and any nearby foils so the spacer can't touch them, then you are fine .. if it is very close or looks like they may touch, then I
would use the insulating washers .... As to grounding the mobo to the case or just the psu .. it will not make any difference, as
the mobo is designed for mounting in a metal tray

 

[Navid]

As you say, the motherboard ground will be electrically connected to the PSU ground after you hook up all the wires. So, the washers have no electrical function.

The washers can help mechanically to provide some room for the motherboard to flex if needed due to temperature variations or when you insert a card and put some pressure on the motherboard.

 

[tempoct]

They are eletrically connected, however, I remember from the old day in college that it is recommended to ground only one spot to avoid ground loop. Not sure how this apply to a computer....

 

[bruceb]

That used to be the case .. a ground loop could cause Hum or instability issues ... However, most new circuit boards
are now Multilayer with ONE Layer acting as a Ground Plane (either the very top or the very bottom layer .. usually the top)
That in effect, eliminates ground loop trouble ... if in doubt as the maker of the Mobo you plan to use .. see what they say

 

[tempoct]

Thanks for clearing this up. I'm using the MSI K8NGM2-FID board. I think they are fine.
I wonder about this grounding thing after talking to a guy at the computer store the other. On any mobo, I believe most mounting holes are not electrically contacted with the ground *but* there is always one hole that is intentionally grounded to motherboard.
Nevertheless, I believe that grounding hole is motherboard designer intention so, I think they might already think about this