Computer Hope
Hardware => Hardware => Topic started by: Lisa_maree on July 02, 2011, 04:10:41 PM
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When changing Motherboards I often see that there has been a lot of effort put into putting red insulating washers on all the mounting holes. Is there a good reason for doing this ? And if it is necessary why don't the manufactures use bushes in the holes.
Thanks
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Thee was a reason. Maybe there is a document somewhere. Some mobo designs had traces too close to the mount holes. So either a isolated washer or a plastic stand off. The current teed is to have all mount points also be ground points.
EDIT: Good Griffie! Just did a quick search and can't believe how many people wild guess with no research or background in motherboard design. If the Mobo maker wants you to ground it, ground the thing!. The metal surface underneath is called a 'ground plane' and some makers want multiple ground points. By design.
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I've used them since Day One...but i'm old school...
Quicker than removing/replacing the MBoard.
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OK. Show and Tell. I will show you mine if you show me yours.
Old Intel type motherboard, now retired for unknown reasons. Has lots of ground pads. Count them. Eight.
http://geek9pm.com/new/old-mobo.jpg
Now look at a close up. The make wants you to ground it.
http://geek9pm.com/new/ground.jpg
(Children tuner 7 show not view the motherboard pix alone. very scary.)
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They are isolation pads, not ground pads. It's a "keep out" area for the circuit trace routing & component pads. Ground (or return to psu) is not connected to the chassis. Motherboards have many layers, component side, solder side, ground plane (internal), voltage plane or planes (internal). At least 4, but could be 6 or 8.
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No disrespect.
They are ground posts.
It is an Intel D845PEBT2
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They are ground posts.
They are isolation pads, not ground pads.
I guess I'm wrong because I always thought that these points are simply for physically mounting the mboard to the case only, and the metal rings around the holes in the mboard are for strength (to spred the load across a broader area on the brittle fiberglass/epoxy board material) so as to not crack the board when the mounting screws are torqued. From what i've seen these points are not connected to any of the conductive traces on the board, and the board itself is non-conductive, so I don't see how they would serve as ground points.
The last machine I built (1st in specs) used metal screws and spacers to mount the mboard to the case with no type of insulation washers, bushings ect. The spacers were simply used as spacers to keep the components on the board from touching the case - not for insulation. The input connectors (http://www.smpspowersupply.com/connectors-pinouts.html) on the mboard from the PSU have several grounds (common) on them. And most, if not all connectors throughout the machine also provide a ground (common) for the circuit that they connect to.
This is just based on my experience. I'm no computer guru. This is just my wild guess. I'd like a link to some info on this subject though.
And if it is necessary why don't the manufactures use bushes in the holes
Very good question! ;)
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The photos I posted above are from a real Intel motherboard. D845PEBT2. On that motherboard all eight of the mounts are to be electrically and mechanically connected to the metal case. It is by design, not an accident not an after thought. This does not apply to all motherboards. It is true of many Intel motherboards.
There are photos by 'experts' mounting that motherboard with plastic standoffs. Yes, it will work with plastic standoffs. But that was not the intent of the team that did the motherboard. The Intel motherboard was designed, layered and prepared for metal standoffs.
But it will work without them. It will work in a Pizza box.
(Anybody remember the Apple Pizza box ad?)
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They are ground posts.
It is an Intel D845PEBT2
According to the spec sheet for that board, it follows the ATX 2.1 standard for mounting holes. The ATX 2.1 standard for mounting holes quite clearly states that the mounting holes are for "mechanical support only". You'll note specifically that the "only" means that it doesn't do anything else, such as being electrical/ground support, which would be utterly stupid and dangerous.
Also, in every board I've seen that features the metal "bracing" around the screwhole for mounting, the metal on the board is Aluminum or brass, or some other non-conductive alloy.
Geek: if you look closely at your power plug, you may notice that it has a third prong. Modern devices use this as their electrical ground. And if you removed that prong because you are living in a old house and somehow think your case and motherboard magically retrofits itself to use aluminum and brass to conduct ground voltage, well, I'm not really sure where to start.
If computers used the motherboard mounting holes and case for grounding, that would have two issues:
1st, the entire bloody thing would be a electrical and fire hazard. And what if the case is plastic? There is no provision in ATX that the case be metal, let alone a metal that conducts electricity; otherwise there would surely be documentation on the minimum conductivity of the case. How would a board conduct ground through a plastic or aluminum case, for example? particularly using a aluminum or brass standoff, as they commonly are, to mitigate the possibility of the very thing you state happens by design.
2nd: where does the power supply get it's ground from? It's own case? But what if the case it is installed in is not a conductor? Then what? I submit the clearly preposterous idea that the power supply get's it's ground from this magical thing called the "GROUND" prong on any modern electrical socket. If you look, you'll notice, quite clearly, that all power supplies require the presence of this prong. Additionally, this grounding is passed along to the motherboard along the clearly confusingly named GROUND wires.
If I recall, however, you yourself have documented that you "hacked" your power cables because you didn't have a three-pronged cord to use. This doesn't magically mean that your computer will use the case as ground, even if it is a conductive material and your standoffs weren't made of brass or aluminum which they always are. It just means that none of your voltages will be measured properly, and who knows what else. I certainly wouldn't trust a machine in such a position.
Electrical power running to the case is not "being grounded" it's called a "short" and is not desirable, and can result in injury or death if mishandled. Or in the hands of somebody who thinks brass standoffs can conduct electricity through aluminum, and then through silicon, as well as a computer magically being earthed.
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According to the spec sheet for that board, it follows the ATX 2.1 standard for mounting holes. The ATX 2.1 standard for mounting holes quite clearly states that the mounting holes are for "mechanical support only". You'll note specifically that the "only" means that it doesn't do anything else, such as being electrical/ground support...
Please document this.
The Intel board was designed for electrical and mechanical connection.
The design is explicit. (Need more more photos?)
At the present time all my stuff is now grounded. Including all electrical things. Except the coffee port. It is a two wire and was sold that way in the local store.
Furthermore, I may be very dumb, but I am not stupid.
Not very much. :||
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Easy to test for yourself. Place an ohmmeter between 2 mounting holes.
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Please document this.
http://www.formfactors.org/developer/specs/atx2_1.pdf
The Intel board was designed for electrical and mechanical connection.
Then it's documentation lies, because according to it's spec sheet it conforms to ATX 2.1. It either conforms to ATX 2.1 or it magically conducts electricity through aluminum and brass. Strangely I'm not seeing the feasibility of a case suddenly making the conductivity of Aluminum and brass high enough so they act as a ground. And if they did, would they not use another material? the material, judging from your images, is probably aluminum. If the case was designed to "conduct electricity to the case" (which would in fact prevent it from being FCC certified and thus saleable) why would they use metals of such low conductivity? Particularly metals that are by and large more expensive to get them plain old steel?
The design is explicit. (Need more more photos?)
Photos of what? you've photographed the metal ring around the mounting holes. Woop dee flipping doo. Even if we presume that the metal is a electrically conducive one, they are still pictures of a few isolated rings of metal that are still mounted using brass and or aluminum standoffs as stock. Note that the standoffs come with the case, not the motherboard, so I'm not sure how the desktop board that claims to be ATX 2.1 compliant would say "oh, but you have to use conducive mounting standoffs, because we want to pipe ground directly to the case, even though it probably won't be grounded and may even be comprised of a non-metallic substance. I also find it strange how this "design feature" absent from any other board I've ever seen or heard of going back to my 286 (which also used brass standoffs) also doesn't bear mention in it's Technical product specifications (http://downloadmirror.intel.com/15337/eng/D845PEBT2_TechProdSpec.pdf).
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That was done earlier. All eight are intrinsically into the board stuff, not just a protective ting around the edge. It ties in the entire common return of the entire board, memory, PCI, CPU, I/I ports, including USB. the whole thing. It is, in fact, the common for the system. All readings are below then limit of my DVM and are not polarized. They are, in fact, ground points. Even ones that look like maybe the are not, really are.
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it magically conducts electricity through aluminum and brass.
Aluminium (UK spelling) is has 61% of the conductivity of copper; it is often used instead of copper in power cables for cost reasons. Brasses range from about 28% downwards. One should not conclude from this, however, that brass should never be used in electrical applications. There are instances where the superior tensile and machining characteristics of brass make it a better choice than copper as long as the sectional areas are increased proportionately to achieve the conductivity that a copper part would have in the application. A brass screw would have the conductivity of a copper one a bit more than one-quarter the sectional area. Considering the screws and standoffs used to fasten motherboards to cases, that quite a current carrying capacity. Think of a copper wire that thick.
(http://www.kp44.org/images/Conductivity1.gif)
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BC, I have already read that many time. It never says the support holes are only for mechanical mounting. In fact, it does not say you even have to use the holes for anything at all.
The board was, is, fabricated with explicit ground points on the underside of the holes.
Next you will tell me that Rose bushes don't have thorns because you have never seen them.
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BC, I have already read that many time. It never says the support holes are only for mechanical mounting.
Hmm, good point. I was reading the bit where it says that three new mounting holes have been added (as in since the previous specification) for mechanical support. On the other hand, the only mention of "grounding" is found in the statements about the I/O shield and why it shouldn't be painted. Nothing about the mounting screw locations having anything to do with grounding. Is that not an ATX specification? If not why does the Intel board manual not mention it either? What proof do you have that any of the actual components tie into these alleged "grounding" screws?
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In fact, it does not say you even have to use the holes for anything at all.
Yes it does, that is implied in the name- "Mounting" holes. You know, for mounting.
The board was, is, fabricated with explicit ground points on the underside of the holes.
Document this. With documents, not pictures. If this is the way they engineered it, would they not have technical documentation about how to make sure it's properly setup and functional?
Next you will tell me that Rose bushes don't have thorns because you have never seen them.
The difference here, is there is a good reason for a Rose bush to have thorns (actually, they are technically prickles), in that it helps the rose plant grow over top of other vegetation, as well as other advantages like reducing animal browsing... in this case, there is no good reason for the "engineers" to come up with this type of non-solution. It doesn't solve a problem. There is already a ground available for the motherboard to use.
aid the rose in hanging onto other vegetation when growing over it.
[/quote]
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hey engineered it,
I have to go to a conference n ow. I will be back later with additional information.
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Motherboards work perfectly well out of the case, resting on e.g. a rubber mat. The "grounding" (power supply return) is provided by the black wires leading to the power connector.
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Motherboards work perfectly well out of the case, resting on e.g. a rubber mat. The "grounding" (power supply return) is provided by the black wires leading to the power connector.
Need to clarify terms.
grounding
power supply return
Are not the same.
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Need to clarify terms.
grounding
power supply return
Are not the same.
OK, well I think I'm done here. I've had more productive discussions with flatulence.
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OK, well I think I'm done here. I've had more productive discussions with flatulence.
BC, You are the one making a stink.
The thread is: Re: use of Insulating Washers
My intent t is to say that they washers are not needed on many Intel motherboards.
They ones I have are explicitly fabricated and prepared for ground contact.
I did not make any statements about power supply wiring options. Not did I imply there were any other wanton connects to the power supply.
In the industry the term grounding with reference to a PC fabrication simply means there is a point or points where it is expected that nan electrical connection be made to the case of the unit. It does not mean any power will be sent into the paint. It is for shielding.
And I never said it would not work if you did not use the ground connections. I did say it will work in a Pizza box, which is true. Not recommended. Violates FCC rules.
Is Intel wasting money on fabricated ground points on their motherboards? I don't know, I never worked for them. I do know that when I ordered a PC board with extra stuff on it that was not needed, my superiors had some words for me. But of course, that was ages ago.Does it no longer matter?
Maybe noways they don't care about those kind of details. Or maybe motherboards are so much more sophisticated that the old school rules don't mean a thing. Haste makes waste.. Apparently not. Everybody wants to use fiber washers where the PC board was peeped for contact. Good for the economy.The fiber washer people need to eat too.
I am doing some photos of another Intel board.
EDIT: Found this:
http://biorobots.cwru.edu/server/howto/buildcomp/mountmobo/
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In the industry the term grounding with reference to a PC fabrication simply means there is a point or points where it is expected that nan electrical connection be made to the case of the unit. It does not mean any power will be sent into the paint. It is for shielding.
the only mention of "grounding" is found in the statements about the I/O shield and why it shouldn't be painted.
the I.O shield isn't connected to the standoffs, though. And it's for preventing interference and try to diffuse the EMI so that it doesn't cause interference.
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An argument with Geek over semantics....who'd a thunk it ? ?
I use the washers ...as i said earlier.
I used to think it just saved the time removing and re-mounting the MBoard...now i see i also saved alot of arguiing time as well...
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the I.O shield isn't connected to the standoffs, though.
It is on the Intel boards I have. Is it not one yours? :D
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Here is a photo from the backside of an Intel motherboard I have in my shop. This motherboard is in good condition, works fine, inside a box or a, rounded to the case or not.
(http://geek9pm.com/pads/intel_mobo_0001.jpg)
If you want to see more photos of this motherboard here is a link that takes you to a folder on my site and you can click on any picture you want to see. I have not put the pictures here on computer Hope. They are quite large and will suck bandwidth. I have leftover bandwidth on my site, mostly because nobody ever goes there.
http://geek9pm.com/pads/
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Easy to test for yourself. Place an ohmmeter between 2 mounting holes.
Good idea. And I did. And the results suprised me. Testing between all mounting locations on my Intel D845GVSR yeilded a result of "0" ohms resistance on 20k DVOM scale between all mounting locations. I don't see where they are connected to the circuit traces, but they are certainly connected somehow. I'm certainly curious as to what significance this has as far as operation. I guess my next test will be running the mboard in a pizza box. Seriously! Thanks for the test idea Geek-9pm. ;) I'll post the results later.
When changing Motherboards I often see that there has been a lot of effort put into putting red insulating washers on all the mounting holes. Is there a good reason for doing this ? And if it is necessary why don't the manufactures use bushes in the holes.
Thanks
Good thread! ;)
Did you mean bushings rather than bushes? ;D
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ground plane (internal),
'Multi layer'. I guess this would explain the 0 ohms resistance between mounting points without visual evidence of a trace connecting them. ;)
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Did you mean bushings rather than bushes?
In this context the words are synonymous. A bush is a hollow cylinder. A bushing is a hollow insulating liner through which a conductor may pass.
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Here is a photo from the backside of an Intel motherboard I have in my shop. This motherboard is in good condition, works fine, inside a box or a, rounded to the case or not.
Searching for relevance...
NOT FOUND.
You claimed:
the entire common return of the entire board, memory, PCI, CPU, I/I ports, including USB. the whole thing.
And yet you just said that you weren't talking about the return circuit, and suddenly you try to retrospectively change your goalposts to (and I'm paraphrasing) "oh I was totally talking about that EMI thing you already mentioned". But you said yourself that it is the common return of the entire board? there is no electrical connection between the mounting holes and any electrically active traces, so how you come to that conclusion I cannot guess.
If you want to see more photos of this motherboard here
Why would I want to do that? I'm not even sure what they are supposed to "prove" or disprove.Testing between all mounting locations on my Intel D845GVSR yeilded a result of "0" ohms resistance on 20k DVOM scale between all mounting locations. I don't see where they are connected to the circuit traces, but they are certainly connected somehow.
The mounting holes will be conducive through the case.. unless it's plastic, I guess. as Salmon Trout corrected me with respect to the mounting standoffs,all metals conduct electricity. Testing on a unused AMD board I have and there is no connection between any of the mount points. Of course that was an AMD board, which no doubt will serve to fuel some additional rhetoric by Geek-9pm. Of course I'm no longer questioning whether there is any resistance between them but rather that there is no electrical connection between the mounting holes and the board traces, as he alleged earlier by saying that the mount points serve as "the entire common return of the entire board, memory, PCI, CPU, I/O ports, including USB. the whole thing." Which is both nonsensical, plain wrong, and he has yet to provide any sort of evidence aside from a few pictures of the board... which are utterly meaningless.
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See my Post above...
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For reference.
http://en.wikipedia.org/wiki/Pizza_box_form_factor
Pizza box form factor
From Wikipedia, the free encyclopedia
The Macintosh LC's typical "pizza box" case
In computing, a pizza box is a style of case for computers or network switches. Cases of this type tend to be wide and flat, normally one or two rack units (1U or 2U, 1¾ or 3½ inch, 4.4 or 8.9 cm) in height, thus resembling pizza delivery boxes.
http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=1366
The pizza box is a plastic carapace now, corrugated for stiffness, a little LED readout glowing on the side, telling the Deliverator how many trade imbalance-producing minutes have ticked away since the fateful phone call. There are chips and stuff in there. The pizzas rest, a short stack of them, in slots behind the Deliverator's head. Each pizza glides into a slot like a circuit board into a computer, clicks into place as the smart box interfaces with the onboard system of the Deliverator's car.
(Read more about the smart box by Neal Stephenson)
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***sigh***
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Thank you for you observations, BC_Programmer. ;D
A volt ohm meter can be used to test for continuity and resistance. (References upon request.) Using a VOM requires understanding, previous training and common sense. If there is continuity between two points, that simply means there is simple electrical connectivity.
The existence of a electrical connection does not reveal how it is being used. Electrical power [low frequency] goes from a source directly ton the object and then returns directly. It does not take side a trip to explore a cul-de-sac.
A cul-de-sac (literally "bottom of bag") is a word of French origin referring to a dead end, close, no through road (UK, Australian and Canadian English) or court ...http://en.wikipedia.org/wiki/Cul-de-sac
Intel mother boars, as well as Gigabyte and many others, have hole patterns explicitly fabricated as ground connections. What you do with them is up to you. Using as a replacement for a power return is never recommended ever.
More questions?
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Intel mother boars, as well as Gigabyte and many others, have hole patterns explicitly fabricated as ground connections.
More questions?
At the risk of sounding slightly repititious, I'm going to once again ask for some references that back up this claim.
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Do you have auto cad or similar program? In the PCB electronics library you wail find a specific template for doing a mounting hole that has solder points and feed thru points for the express purpose of making secure connection to a screw, post or washer that covers the hole. If no connection is wanted, you just specify a hole in the PCB with no trace pattern and no solder mask.
It has been almost ten years since I did any PCB work and I no longer have a electronics template or any CAD on my computers.
I showed you a photo. Do you need the actual template ton to recognize what nit is?
Maybe somebody reading this has a PCB layout program and will explain what a mounting hole template looks like and what i is used for. The template has three parts to it. The copper trace, the silk and then hole-through. It is a bit of a bother to use nit just for decoration.
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I'll interpret that as a no, then.
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No, you prove that it not a grounding hole. You have never given any proof that these holes are not grounding holes. You do not know what they are for. You don;t want to know. You make some non relevant reference to some other issue and claim that constitutes a logical proof of what you imagine in your day dreams.
(http://geek9pm.com/pads/intel_mobo_0001.jpg)
Please, prove that it is not a place to make contact with the case of the computer. Tell us please what is it? What do you see? Do you know what a motherboard bottom looks like? Have you ever looked at mortarboard before you install them. Of course not, you install them on any moonless nights so the light of truth will not destroy your fantasies.
The only reason I post this is not to correct you, which is impossible, but to warn others -
not to drink that strange Kool-Aid you have.
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Good idea. And I did. And the results suprised me. Testing between all mounting locations on my Intel D845GVSR yeilded a result of "0" ohms resistance on 20k DVOM scale between all mounting locations. I don't see where they are connected to the circuit traces, but they are certainly connected somehow. ...
Only when mounted to the chassis, they are connected to each other & the chassis. They don't connect to traces or layers in an ATX motherboard application, but could in other "custom" applications.
No, you prove that it not a grounding hole. You have never given any proof that these holes are not grounding holes...
I qualify myself as an expert witness. I used to design computer circuit boards for a living. You can call them grounding holes, you can call them mounting holes, or whatever you like. Grounding is not shielding & is confused or mislabeled by many so-called experts. The fact that it's in a PCB library means nothing. If the designer pulls a grounding pad instead of a mounting pad, it matters not & indicates nothing. When the board is mounted, the screw head connects the solder pad to the case. So what? It doesn't connect anything else on the circuit board to the case, except for the shield of one of the connectors, IF the specification requires or recommends it, & most specs do not.
It may appear to be a grounding hole, but it does not function as one!!!
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Thank you Computer_Commando,
You answer makes sense. If it is not connected, it does not matter what it looks like. If i not connected, then the insulating washer would only help protect from a mount that off center and threatened nearby traces.
I appreciate that you have done PCB work, so you understands what I mean. The pattern in the photo above would or should be used when a connection is wanted. It requires trace, solder mask, silk and hole through. As you know, hole-through is a significant cost, but not excessive. And yes, the artist might have used it for nothing. But that is not was n happened. He put in in the net. Every one has conductivity intrinsically.
Yes, the term 'ground' is overloaded. Thee is a set of traces and wires the tie into the power connector. The designation of that set is called GND in the specs. I am referencing to that set of traces and wires, visible or not, that run to the GND group of the power connector.
With the board removed, nothing connected to it, on a wood table, there is continuity from the GND to several points on the motherboard.
Personally, I have seen some PCBs that nave only a hole and no trace, solder or hole through. Just a hole in the board. But to date, I have not yet found any motherboard with the obvious pattern that did not have a connection to the trace/wire group is called GND at the connector. Call it what you want, it has conductivity to the group when the board is out of the case. I belie I said that earlier. All eight holes I in the first picture have continuity when the board was out of en case.
I am going to check every motherboard I have to see if that hole pattern is ever used without conductivity to the GND group.
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All eight holes I in the first picture have continuity when the board was out of en case.
you said: these points act as:
"the entire common return of the entire board, memory, PCI, CPU, I/O ports, including USB. the whole thing."
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Thank you. Yeah, thaht was what I siad. All boards I have tested so far, out of case, on the table, have electrical continuity from the solder ring inside mount hole hole to the other points on the motherboard that electrically connect to the power connector GND. This GND thing electrically ties into parts of the memory, the CPU, the PCI and other points on the Motherboard. Must be like a spider web in there.
The ATX specs say there has to be reversal connectors in the Molex that are GND. Boy, did they get that wrong! They don't do anything, barbecue tGND tie into the mounting holes. which are only used for mounting, never anything else. Somebody tell them the GND are useless.
Somebody said the motherboard has no connection to the mounting holes. If that is true, then then logically parts of then CPU, the PCI, the memory and the GND connectors have no purpose. They do not don't anything because expertise have told us that the muting rings have no connection to the motherboard.
So therefore, Intel, Gigabyte and others are running a lot of unneeded wires inside the motherboard. Now if can get the vital information to them, perhaps they can build better motherboards and stop just messing around with their fancy PCB auto-router tools. They need to hire some people that know what they are doing.
Good thing we have this post! We are making progress! Using the simple rules of logic, we do not need any of the black wires in the power cable harness. Barbecue they are part of then useless network the ties into the mounting holes. Think of how this will simplify our new builds!
{Had to us the green color because wry sarcastic color was all used up.}
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The mounting holes will be conducive through the case.. unless it's plastic,
I tested my board with it not mounted in a case.
Testing on a unused AMD board I have and there is no connection between any of the mount points.
Are you saying there is no continuity (infinite ohms resistance)?
or
Are you saying there is no connection between the mounting hole and the traces on the board?
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Only when mounted to the chassis, they are connected to each other & the chassis. They don't connect to traces or layers in an ATX motherboard
Not true in my case. My test were done with the mboard not mounted.
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But it will work without them. It will work in a Pizza box.
(Anybody remember the Apple Pizza box ad?)
I guess my next test will be running the mboard in a pizza box.
Quote
http://en.wikipedia.org/wiki/Pizza_box_form_factor
Pizza box form factor
From Wikipedia, the free encyclopedia
The Macintosh LC's typical "pizza box" case
In computing, a pizza box is a style of case for computers or network switches. Cases of this type tend to be wide and flat, normally one or two rack units (1U or 2U, 1¾ or 3½ inch, 4.4 or 8.9 cm) in height, thus resembling pizza delivery boxes.
Quote
http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=1366
The pizza box is a plastic carapace now, corrugated for stiffness, a little LED readout glowing on the side, telling the Deliverator how many trade imbalance-producing minutes have ticked away since the fateful phone call. There are chips and stuff in there. The pizzas rest, a short stack of them, in slots behind the Deliverator's head. Each pizza glides into a slot like a circuit board into a computer, clicks into place as the smart box interfaces with the onboard system of the Deliverator's car.
(Read more about the smart box by Neal Stephenson)
I thought you meant a cardboard pizza box lol. ;D
But I did run the D845GVSR mboard with all the mounting screws removed and the board resting on rubber grommets (insulated from the case). It started up and ran just fine - no change from being mounted. So, although all the mounting holes do test 0 ohms continuity between them when the board is not mounted, there seems to be no need to "ground" the board to the case.
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This thread is now solved.
All we need now is somebody to tell us what the answer is. ;D
Mac and PC ad Pizza Box 8)
http://www.youtube.com/watch?v=e32OEku5el8
PIZZA BOX COMPUTERS ::)
http://www.youtube.com/watch?v=inph0y_LxQs
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there seems to be no need to "ground" the board to the case.
It would probably help to keep with RFI emissions down. It may be an FCC (or local equivalent) requirement.
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Hi Guys,
Thank you for giving so much thought and input into my question. It all makes great reading. Thank you again :)
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Well, I don't know if I'd call it great reading but I,ve learned a few things. It's a shame we haven't really answered your original question:
Is there a good reason for doing this ? And if it is necessary why don't the manufactures use bushes in the holes.
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Best answer was by Patio and is a Classic answer.
"It makes it easier to take the board out."
That answer is piratical, accurate verifiable.