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Grounding system with no case

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December 1, 2011 1:10:30 PM

I have an emulator based arcade I built a few years ago..I want to upgrade it using some more recent parts i have and I'm thinking for convenience i'd rather mount everything to the inside compartment of the arcade rather than have an actual computer case in there.

any suggestions for grounding the motherboard? it would be mounting to wood with a formica-like surface, which i'd think would be fine, but i think i need some sort of spacer so the board isn't directly touching.

Is it ok to set the power supply, hard drive on the floor of the arcade or would that present heat issues?

also, with an open back, do you think id still need fans?

thanks to anyone smarter than me.

More about : grounding system case

a b B Homebuilt system
December 1, 2011 1:29:02 PM

The 24-pin motherboard cable has ground cables going from the PSU to the motherboard. Therefore the motherboard is grounded to earth if it is connected to the PSU and the PSU itself is plugged in.

The same is true with my metal case sitting on a wood desk. The motherboard isn't really grounded to earth unless the PSU is plugged in because there are insulators between the case and earth.

While you could mount the motherboard straight to the wood, small standoffs would be nice because it will allow air to move under the board more freely. If you have it mounted vertically, convection can carry the the hot air up the back of the motherboard into the open space higher up in the case. Granted, most of the heat comes off the front where the heatsinks and components are, it might make a small difference.

I don't know if you'll need cabinet fans, but just monitor the temperature. If the temperature gets too high after a gaming session then add some fans to the back of the arcade cabinet.

The power supply can be set on the floor, just make sure the fans aren't covered (so flip it upside down if the fan is on the bottom). The HDD can also sit on the floor and should be fine.
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December 1, 2011 1:30:10 PM

My brother built an arcade like you are saying... but i think he kept the pc in a case. Either way... I have "tested" PC's by laying the components on a bench without a case and had no issues. The power supply grounds the motherboard(i believe)...

the heat issue would mainly occur with the hard drive... but may not be a problem. if you could lift it off from directly contacting a flat surface, that would be ideal. Power supply should be fine as long as you don't block the fan.

open case, shouldn't need any extra fans..... adding one wouldn't hurt... because you will probably have the "open" back against a wall..?
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a b B Homebuilt system
December 1, 2011 1:35:55 PM

I have done lots of funky stuff like this in my time. In a perfect world the mother board should ground through the main power Connecter to the PSU, Which in turn is grounded to the house through the third prong on the power wire. Look at the main connecter of the PSU the black wires are all grounds.

You should use a couple thin wood screws and a few plastic spacers to keep the mother board up off the wood when you mount it. You dont want the parts on the bottom of the board to get crushed if you screw it down to tight.

If you are really worried about grounding it might not be a bad idea to just take some bits of wire and attach one end to the mounting screws of the mother board, one end to the mounting screws of the HD, and finally have it all tie back to the mounting holes PSU. This would simulate a case. The PSU is the key to grounding to the house.

This would not be as good as a metal box when it comes to protecting the parts from static shocks. As we know electrons flow away from the internal components and travel on the out side of the metal case when you shock the case. This is why it is safe to discharge your static on the case be for you open it up.

I think you will be fine.

As for just leaving the PSU and HD on the floor of the comparment that should be fine, as long as the cabinet does not get moved around much.
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a b B Homebuilt system
December 1, 2011 1:43:35 PM

bucknutty said:
You should use a couple thin wood screws and a few plastic spacers to keep the mother board up off the wood when you mount it. You dont want the parts on the bottom of the board to get crushed if you screw it down to tight.

If you are really worried about grounding it might not be a bad idea to just take some bits of wire and attach one end to the mounting screws of the mother board, one end to the mounting screws of the HD, and finally have it all tie back to the mounting holes PSU. This would simulate a case. The PSU is the key to grounding to the house.

This would not be as good as a metal box when it comes to protecting the parts from static shocks. As we know electrons flow away from the internal components and travel on the out side of the metal case when you shock the case. This is why it is safe to discharge your static on the case be for you open it up.


Good point about crushing the pins on the back. Didn't really think of that, but then again I wouldn't torque it down either :D .

As for static shock protection a wood case is just as good as a metal case. If you can't touch it, you can't discharge static electricity to it. The only precaution needed would be when removing/changing parts. You have to make sure you are at the same potential as the components inside the wood case before touching them.
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a b B Homebuilt system
December 1, 2011 1:46:34 PM

fun topic... I love putting computers in unconventional places.
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December 1, 2011 1:58:32 PM

What about drilling and mounting a computer case sideways to a wood shelf in the cabinet. Mounting the mobo should definitely include spacers. There are structural and heat issues involved. I'd just cut an old case up and use it to have an easy mount and rack solution so I don't have to measure and fabricate everything out of wood. Measuring for spacers will be a pain, strapping the PSU down will be a pain... Don't do work you don't have to. And all your components in a case with be smaller and cleaner and stronger than messing with wood.
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December 1, 2011 2:11:01 PM

Kronk42583 said:
What about drilling and mounting a computer case sideways to a wood shelf in the cabinet. Mounting the mobo should definitely include spacers. There are structural and heat issues involved. I'd just cut an old case up and use it to have an easy mount and rack solution so I don't have to measure and fabricate everything out of wood. Measuring for spacers will be a pain, strapping the PSU down will be a pain... Don't do work you don't have to. And all your components in a case with be smaller and cleaner and stronger than messing with wood.



good idea, maybe i can take the mounting plate at least out of an old case. i also read in some searching on other forums that you can cut up the casing of a bic pen to use as spacers as well.

and to answer someone elses question about being against the wall..the design has some space for air to escape - 6" x 18" (estimate) on each side of the case even if it is against the wall...plus there is an opening in the top if air makes it through crevices..though a fan might still be a good idea to at least circulate.
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a c 78 B Homebuilt system
December 1, 2011 2:13:24 PM

I disagree with Kronk, cases are a generally necessary evil.

Not because they are beneficial, but because they keep people from doing stupid things like stepping on the motherboard.

If you have a wood enclosure that will prevent you from touching the motherboard while it is operational, that should work fine. An arcade machine frame would work for this.

The ideal would be to not use a case and to not touch the motherboard because that would allow for heat to easily rise away from the motherboard rather than keeping the heat contained in it.

If you are willing to try to engineer a caseless solution, I am willing to assist.

I would, however, still recommend that you try, if possible, to use more fans than just what is on the video card and CPU. That would work, but more would be ideal.

If it were possible to orient more case fans somehow toward the board than just those two, that would be ideal. If not, its probably not a big deal.

I don't think you would run into any problems mounting the PSU horizontally on the bottom of the arcade machine if you had spacers to hold the motherboard an inch or two off the bottom.

Vertically on the side should probably work just fine too, though it may be harder to mount like this.
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