custom case from scratch question

[Tazon]

i am building a custom case, and came to the point of mounting the mobo. i believe the thing to watch here is that the mobo doesn't make contact/ground with the case. is this all? or is there something else i should be watching for?

my idea is to mount the mobo on a plain sheet of rubber. any problems with this?

emilio

[da-gokesta]

the only issue i would see is overheating

[desalien]

active cooling on the backside of your mobo could be a solution ...

[woods]

spacing between the mobo and mount tray is important along with grounding. All AGP/PCI cards have a tab that goes past the mobo. Rbber would not be a good idea considering the fact that you need a stiff mounting surface that you can use as a ground. If you go with a sheet of alumuinum, steel, ect. then you should not have any issues. If you goe with a non conductive material, then lexan or plexi would be good as long as you ground all of the mount holes. You could use some rearwindow defoger repair kit. or you could use some wire and put it through all of the holes before you thread the risers into them . Make sure you leave enough extra wire so that you can conect it to the p/s case. good luck.

[Captain Slug]

Plus the backside of the board has alot protruding out of it so you aren't working with an easily mountable flat surface.

If you need stand-offs, take a few case screws to Lowe's or Home Depot. They do have stand-off which should work fine for you project.

[Tazon]

mmh let me get this straight. so i WANT the mounting holes making contact with the case? and i want the PCI/AGP tabs making contact with the case?

[Captain Slug]

Originally posted by Tazon
mmh let me get this straight. so i WANT the mounting holes making contact with the case? and i want the PCI/AGP tabs making contact with the case?
No, if you start screwing you motherboard down to a flat surface you'll start to warp the board, even if you put and interface material inbetween the two.

Use stand-offs

[diggingforgold]

You want the screwholes to make contact with the case (to ground the motherboard). Grounding is for safety for yourself as well as your computer parts.

You do not want the case to make contact with anything else other than those screwholes (or else you will short the motherboard to the case). Shorting occurs when electricity skips over its designed course (on the motherboard) and hops somewhere else (in this case, by using the case as its short route) where it's not supposed to be. A short means electricity is taking a shorter path, and you don't want this to happen on complex electrical components such as mobo's.

The case can and should also have some sort of ground contact to the powersupply box. In a normal case, when you ground your motherboard to the screws, the screws connect to the case (which in itself can act as a ground since it's large enough), the case connects to the powersupply and the power supply connects to your houses/apartments electrical system ground wires that actually go to the ground (earth) which is an almost unlimited source of absorbing electricity. Of course this is extreme. I doubt you will have lightning-bolt strength power running through your motherboard. But it's always good to ground your motherboard to your case by using the motherboard screw holes (as those tiny leads that you may see that go to the holes are probably your motherboards ground connections).

If you still want to keep your idea, you probably could mount your motherboard to rubber. I've run my motherboard out of my case with no grounding on cardboard, and it seemed to work fine. But I think the general rule is to indeed ground your motherboard how it was designed to be grounded- by using the screwholes. If you want to, you could try to solder or connect wires to each of the screws that you attatch your motherboard to the rubber with. Then you can bring those wires to connect to some non-voltage part of your powersupply (like the psu case) for a way of grounding your mobo- and it will work perfectly. If your case is made out of something that can carry and safely dispurse electricity (amongst a wide area), you can connect those wires to your case. But I would stick with the psu, as it connects to the ground wires in your house.

[Tazon]

thanks a lot this was really helpful