motherboard mounting and earthing

[airflow]

Hi,

I'm playing with an oldish computer and it has an ABIT ST6 motherboard.
I've been having some issues with it, but for now I've got some general motherboard mounting questions

When mounting with studs, there are spacers/washers that look to be non-conductive
http://img156.imageshack.us/img156/7655/screws.jpghttp://img156.imageshack.us/img156/7655/screws.jpg


I presume these 'washers' are meant to be in between the motherboard and the screw head in some cases?
http://img156.imageshack.us/img156/4752/ide.jpghttp://img156.imageshack.us/img156/4752/ide.jpg



Then again, the mounting holes in the mboard have a metal ring around them. So I thought maybe the screw is MEANT to contact this metal ring?
http://img22.imageshack.us/img22/3576/usb1czw.jpghttp://img22.imageshack.us/img22/3576/usb1czw.jpg

Is the motherboard supposed to be earthed to the case in some way?

Should I make sure there are non-conductive washers underneath all the motherboard mounting screws?
Should they be on the other side of the board as well - between the stud and the back of the board?

The fact that at some mounting points I havn't even got plastic spacers there could that be a big problem? (where a hole doesn't line up for using studs)


cheers,

Adam.

[airflow]

Also I found these other spacers that came in the screws box with the case (I think)
http://img297.imageshack.us/img297/9813/spacers.jpg

Has anyone seen this type of spacer before and know how well they work?
They are for mounting the motherboard onto the case right?

[The Wise Monkey]

You should just put the brass spacers into the case at the marked ATX points and then screw through the motherboard holes into the spacers to hold it in place. The other washers and things aren't really necessary, but you can use them if you want. Just make sure that they don't touch any metal on the motherboard as it might cause a short, which could break the motherboard in the worst case.

I think that the metal rings around the mounting holes on the motherboard are just for support.

IIRC, the motherboard is grounded via the PSU, so there should be no contact between the board and the case at any point. Well, except for the back panel. :)