How Much do Motherboards Rely on Grounding ?

[wwswimming]

one of my jobs i was working with a guy on a really sensitive amplifier for a network analyzer and i remember he kept saying, "put in another grounding point". we had a little circuit board a little smaller than a credit card, grounded in about 11 places.

i think the conventional ATX board is mounted in 9 ?

anyway all my engineering play life (career) i worked on a lot of microwave and RF stuff and a big #1 design rule was, everything had to be well grounded, isolated, worry about EMI, etc.

well, the circuit boards that we run a 3.6 P4 or a 2.2 GHz Opteron on, is technically running at microwave frequencies ... not exempt from the laws of physics ... so all the rules about transmission lines and grounding apply.

so, since my 3.6 P4 works pretty good in an acrylic case (would it OC better you think if i put it in a metal case, all else equal ?), i can only conclude that all of the grounding requirements of the high frequency circuitry are met within the geometry of the board itself.

do serious OC'ers always do their work in metal cases or with the motherboard mounted on a metal surface ?

thanks for the info.:sun:

 

[Navid]

Originally posted by: wwswimming
i think the conventional ATX board is mounted in 9 ?

Yes. But, those 9 spots do not have to be electrically connected. The motherboard is grounded through all the cables that go to the PSU.

well, the circuit boards that we run a 3.6 P4 or a 2.2 GHz Opteron on, is technically running at microwave frequencies ...

Not really. Those frequencies you have listed are the frequencies that are present only on the CPU. They are generated on the CPU by a clock frequency multipler (PLL). The external frequency that is present on the printed circuit board (motherboard) is limited to 200MHz. If overclocked, it can go higher. But, still limited to 300 or 400MHz.

not exempt from the laws of physics ... so all the rules about transmission lines and grounding apply.

That is true.

so, since my 3.6 P4 works pretty good in an acrylic case (would it OC better you think if i put it in a metal case, all else equal ?)

I don't think so.

do serious OC'ers always do their work in metal cases or with the motherboard mounted on a metal surface ?

What may benefit from a well isolated PC is not the PC itself. It is the operation of sensitive radio equipment that may suffer from interference caused by the PC.

 

[MagnusTheBrewer]

Bottom line is if you were to ground the MB directly to the case you may not be able to boot at all and worse case fry your MB.

 

[wwswimming]

http://www.tomshardware.com/2005/09/06/...from_all_american_computers/index.html

Liquid XS from All American Computers

long URL. anyway, the Liquid XS was among the best in the bunch, OC wise, and it was in an acrylic case.

 

[Big Lar]

My case is Homemade by myself, been running it for about 5 years now. It is made of Oak, and is double wide, with the mobo on 1 side, and the drives on the other. My Only gound persay is thru the electrical system, ie PSU,LCD, etc and no other. I have never had any ill affects as to OC'n, nor anything else.

I believe that if the electrical system of the actual home/office is done correctly, you are good to go, at least that is my expierience.