z77 minimum clearance to plate ?

[sturoc]

Am attempting to install the z77 Pro 4 in a Maxtop rack case for our recording studio's new DAW.
Problem is there were no standoffs supplied. We had some extras from a tower case but they were thread size (6-32), rack case is M-4 and are too high for it to line up to the i/o shield panel anyhow.

When I get the correct standoffs, the MB appears to be pretty low to the underside mounting plate I am talking millimeters here.
What is the minimum acceptable distance between the MB and the underneath mounting plate ?
Should I put a thin sheet of insulation on the plate just in case ?

Strange how this case did not include proper standoffs and that the above is an issue with it.

and btw: Glad to have joined the forum here !

[parsec]

Good question, I am not aware of any minimum distance spec. The I/O panel will determine the spacing, as you know.

IMO, as long as any component leads, etc, are not touching the case/tray under the mobo, you are fine. A thin insulator is a good idea, thin being the keyword.

Case design will dictate the size of the standoffs, and not including any with that case is strange, I certainly agree. I've never used a rack style case, are their standoffs shorter? In a standard PC case, the clearance is only a few millimeters.

[sturoc]

I threw the question to ASRock tech support as well, here is what I got back from them:

We’re not recommended to using non standard standoff screws to avoid damage the mainboard.

Of course they don't, but it did not answer my question either.
Sent them back a pointed reply to address my actual question.
I see that the shorter height standoff that's out there making a 4-5 mm space ( way less than 1/4" ) should work. but man it looks close even though NO contacts,traces, pins of caps and other components will touch. I wonder about arcing ?

[parsec]

I wouldn't think arcing would occur, given the low voltages used on a mobo, 12V maximum, and mostly much less. Is the metal under the mobo painted, or bare metal?

If you are brave and competent, and have a sharp, small wire cutter, you could trim back the longer wires, etc, on the bottom of the board. I have done that in the past, without any problems. Just don't cut into the solder points, obviously.

I've also used electrical tape on the case, on the area under the mobo, when I was concerned about potentially shorting the bare contacts on the board to the PC case. I didn't cover the entire area with that tape, just where I thought it would help.

Thin, clear plastic like that found in packaging (like on 120 - 140mm fans) can be cut to shape and taped into place for an insulator.

[sturoc]

Good point on the voltages. I'll a good look at all the pins sticking out, seems like nothing is too long.
The mounting plate is painted black and does not scratch easily.

I wonder if using a piece of the anti-static bag the MB was shipped in would work? tape it or tack with hot glue to the plate ?

[parsec]

That bag sounds like a good idea. They seem to have a coating of some kind on them, as they have a dark, smoky color. I don't think that would be conductive, probably an added insulating shield, but I'm not sure.

[sturoc]

Researching is like finding gold sometimes .
From a website:

"There are three types of anti-static bag: the pink ones which incorporate hygroscopic chemicals into the plastic, and the opaque black ones which are filled with carbon powder, and the shiny transparent grey ones which are coated with very thin metal. The pink ones are conductive because they remain moist all the time. The other two contain conductive materials. None of them are excellent conductors (they're not like metal.)
But all of them are terrible insulators.
The purpose of an anti-static bag is to prevent any contact or "frictional" charging and to let any surface charges migrate rapidly. But also, the bag must limit any large pulses of electric current which occur when charged objects touch the bag. Metal foil is no good. Suppose you dropped a highly charged computer chip into a metal foil bag? When the pins on the chip touched the metal bag, ZAP, it kills the chip. Instead you want to let the charge leak away slowly within a couple of seconds. An anti-static bag needs to be conductive, but not as conductive as aluminum foil, that's why these bags use somewhat- conductive plastics. "

So that kills my option of using it as an insulator underneath the MB.
Still waiting for ASRock tech support to get back to me with an official answer on clearance distance.

.

[parsec]

I just had a feeling about those bags, good thing you checked, I never knew any of that, thanks for posting that info.

IMO, I would not wait for an official answer, will it make a difference to you? Will you get another case and check the standoffs somehow before you buy it? What will the spec be, from the bottom of the board to the case? That is worthless, due to the variations in the lead lengths.

You know how tall standard standoffs are, if that case needs shorter ones then put something between the board and case.

Put some duct tape on that area of the case and move on.

[profJim]

The forum recommendation has been to never place an anti-static bag under a motherboard when you are testing a system with the motherboard outside of the computer case because of their conductive properties. This obviously applies when the motherboard is installed in the case.

[sturoc]

Thanks for the second confirmation of the anti static bag theory ProfJim.

The rack company is sending, hopefully, the proper standoffs.
Mean time I have started assembly outside the case with the MB on the foam it was packed in, it is pretty firm.
this way there will be no undo flexing when mounting memory, cpu cooler ...

Thanks for the replies and good to have found out the real story bout them bags !