I've built several systems in the past and by following the norm simply put the screws through the motherboard and into the back pegs. Looking at the holes in the motherboard I see a bit of metal around each hole. It's not really solid, but it's there. The whole case is metal, so I couldn't help but wonder if by grounding the mother board to the case it could cause minor problems sometimes. I've also heard of a rare person here and there having a weird problem where their system won't start with the board in the case. But it may not have been related to the screws and holes, but a power supply incompatibility instead from what I remember.
At the same time I figure most people just screw down the board and it works fine as it does for me. But looking in the pile of screws I got with my Antec 900 case, they give me like 7 or 8 little paper washers, which then make me wonder if I should use those, LOL. So I turn to my asus motherboard manual which simply says to screw down the board. And for all I know, Asus WANTS the board to be grounded to the case with the screws for some important reason. So by putting washers I could be defeating what they wanted. Does anyone know if it even makes a difference?
Here is a picture of an Asus board. It shows the hole and the metal around the hole in a pattern like most boards have. There is no screw in it, but you can see the threads behind it.
No washers are needed but the correct screws should be used. In at least one instance I've heard of a MB fried because the builder used screws with a wider base. The correct screws will not have a flange around the head.
Yup the washers aren't necessary, just make sure that you use the small button head screws rather than the ones with a flared base and that the screws are long enough to get a decent bite into the standoffs that are screwed into the case that the motherboard will rest on.
I guess some motherboards have special grounding requirements. I just turned on my system for the 1st time and went into BIOS successfully. No HD's yet, but that's next. So it looks like it's running good at this point with no washers. Thanks for the tips aziraphale, and boonality.
I strongly believe the board 'wants' to be grounded through those screws, so no washers. The moboPCB is likely a multilayer board and there's a separate ground plane inside the board. Normally there shouldn't be any meaningful currents going through those screws, the ground plane is mainly meant to give stable groundlevel for the datalines and thus reduce crosstalk between the lines and to reduce other interferences as well.
It'll work with the washers and outside the case aswell though, so it's not criticall as such, in those cases the ground plane is left floating in some not-so-well defined potential and it will likely decrease the boards resistance to outside interferences and lower signal-to-noise ratios for the datalines. Might have some effect on the max overclock the board can handle as well.
Or at least that's how I've understood it..
edit: just checked all the stuff I got with my latest build and didn't find any washers what so ever...
I've got the 900 as well and got some of those paper washers for my 680i...but not enough to match the amount of screws needed; i just happened to have extra. either way, it most likely doesnt matter. I think you would need them if there wasnt any metal around the holes on the motherboard (this seems like it's for grounding).
But yeah, just make sure you tighten up the standoffs before screwing everything down; last think you want is for the standoffs to be turning instead of the screws when your trying to take the mobo off...
The screws do ground the motherboard. But they make ground contact where ground contact was intended to be made. The holes where the screws go are isolated from the rest of the components on the board.
The washers supplied are intended to be used to mount the board.
They are not for electrical insulation purposes, I don't know where everyone gets this idea from. They are simply washers to hold the board snugly without having to tighten the screws to the point of pinching/tweaking the board.
If supplied, I use them, if not, I don't.
Either way, if you follow directions and place the proper number of standoffs in the correct places, use the correct screws, you seldom have any problems.
Jitpublisher has this one spot on. As pointed out by many, you don't need the washers as part of grounding the motherboard. The washers allow you to cinch the board down snugly without pinching the board. Also, they allow for a small amount of vibration to be absorbed without loosening the screws - and decreasing the noise from the system.
How much noise you ask? Um.....4-6 paper washers worth I'd think.
To add my 2 cents - agree with the majority, skip the washers.
The only time I have used the washers was on an old build with a POORLY designed case. My graphic card would not seat properly. I added metal washers between the standoff and the case.
ocfun made a very good point along with merman link. There is a very big differnce between a DC ground and a AC ground when it concerns High frequnces. On a ground plane one screw may provide a good DC ground to the to the entire ground plane, BUT not a good AC ground.
If isolation was required I would use nylon screws and washer between board and standoff.
Reference MrsB - " ...Provided with case ... always use". Poor idea as Case manfu has no idea which motherboard you are goning to use and said grounding scheme.
I use them. If grounding is important they contact at the bottom between the stand-off. I feel there purpose is so that you can tighten the screw without it biting into and scraping the motherboard pcb. Simple as that and nothing to do with insulation.