MB install question

[grim122]

i have an old intel 440BX mb im installing and i have a stupid question. do i need the fiber washers to insulate the standoff screws or not?
none came w/the case hardware and i know newer mb's don't need them.

 

[BentValve]

Originally posted by: grim122
i have an old intel 440BX mb im installing and i have a stupid question. do i need the fiber washers to insulate the standoff screws or not?
none came w/the case hardware and i know newer mb's don't need them.

Not only do they not need them but the motherboard may be damaged or not work properly if you use those washers on newer boards. I think you might want to find some for that old board if it was using them before.

 

[grim122]

it was given to me new(unused) so i dont know if it was using them

 

[Big Lar]

This isn't gospel by any means, but I never used the washers on any bx setup I ran in the past.

 

[Lord Evermore]

As best I or the people I know can figure out, the fiber washers only contribute to not scratching the silvery foil around the screw holes. I've never used them. I've always assumed that allowing the screws to touch the silver foil helps to insure a solid grounding to the case.

 

[Zepper]

The washers are to allow for heat expansion - not insulation or any other reason. I try to have at least one or two screws making full contact nearest the physical center of the board and the rest with washers. If you keep your box reasonably cool, it probably won't make any diff.
.bh.

 

[Lord Evermore]

I somehow doubt the screws or the brass mounts get hot enought to show significant expansion which would cause compression of the board further than that of tightening the screws, given that a heatsink clipped to the socket gets much much hotter and doesn't expand enough to break anything. I'd have already compressed the fiber washer anyway during mounting, there wouldn't be much left for it to compress. Even in a badly ventilated case, the case temperature only gets up to "muggy" temps, and the screws aren't making contact with anything that's actually getting hot.

You say they're for heat expansion as if you're sure of it. Where did you get the information? I've never heard that even as a suggestion before.

 

[compudog]

I've never used them on BX era boards. I have used them (and some times even electrical tape as well) on older 486 and socket 7/super-7 boards. Some of these boards wouldn't post without them. You should be fine without the washers. I never head of the heat/expansion thing either and have been doing hardware for the last 10 years.

 

[BentValve]

Yeah I don't buy that one either Evermore.

 

[Zepper]

Yeah, and I expect you guys are both mechanical engineers... The whole motherboard expands and contracts with thermal changes (the case and mobo mounting plate do too). Granted not much but the fiber washers do allow for it (if not overtightened) and help keep the internal stresses to a minimum (ponder why the screw holes in the mobo are so much larger than the No.6 screws used in mounting it?).
. But as I said, probably not required - just best practice (which in times past they actually tried to follow).
.bh.

 

[Lord Evermore]

And I ask again whether you have actual proof that that's why they're included, or if you're just making it up because it sounds like it might be right to your oh-so-amazing mechanical engineering brain.

 

[Zepper]

I've been doing small computers for 22 yrs. (built my first one from a Heathkit with discrete components - transistors, resistors, capacitors, diodes, crystals etc.) - I don't need some "authority" to tell me what the correct answer is - though I probably read it in some early edition of Mueller's "Upgrading and Repairing PCs" or one of those 'Build Your Own PC" books - I've read so many they all blend together.
. If you don't understand how knowledge and logic can lead to the correct answer, then you probably voted for Clinton and Gore (or maybe even Nadir [sic] :disgust: )... I have decided that this is the best answer for ATX where all mounting points are done with screws (in the days of AT most were plastic standoffs w/ plenty of play), but I have also stated that they are probably not really necessary any more - if the builder isn't ham-fisted.
.bh.


Here's my logic:
1- Most mobo mounting holes are thru-plated.
2- Their stress pads are tinned (tin/lead solder) which flows under stress (lubricant).
3- They are all connected via the thru-plating to the ground plane.
4- Do the washers protect both sides and thru the holes? Then not for insulation.
5- No luricant or protection needed unless the screw heads have teeth on the bottom (shouldn't be used for mobo mounting anyway - just for metal-to-metal).
. So you tell me what is left for the washers to do. Oh yeah, they do provide some protection from over-tightening by the ham-fisted and I've used them as shims to true up an uneven mobo or compensate for a short standoff or a long screw. And back in the day, they could be used to keep screw heads from contacting nearby traces, but I haven't seen any mobos w/o stress pads that are much larger than the screw heads for ages - guess the mobo mfrs learned their lesson...
.bh.

 

[Lord Evermore]

Logical steps can easily lead to the wrong answer, when there is more than one possible answer. If you haven't been told by the makers that actually put the washers in, or some other "authority" that was told by the makers, then you could still be wrong. You just happen to have knowledge that makes you confident that it's the right answer. If you can't show someone else an authoritative answer, or don't KNOW that you got the answer from an authoritative source, then you're still just someone giving his own opinion and reasoning.

Oh yeah, and one doesn't need to have been around when computers were built using individual components to be able to be knowledgeable about computers and the functions of the parts of them. People that have been doing something for many years can still make mistakes while someone who's only just started might get it right. Your activity with computers for 22 years just makes me think you're old (in the sense that anyone older than me is old), not that you're necessarily smarter than me, nor would I immediately trust your every word as gospel, I'd still want some proof of something which doesn't sound like it's definitely right.