How Much do Motherboards Rely on Grounding ?

Metal Case vs. Acrylic Case for serious OC'ing

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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.

I have a old Dell L600R for close to 7 years. And it has been ungrounded for almost all those years becouse the grounding on the power cord below the + - thongs fell off one day when we unpluged it. It runs 24/7 and never has a problem and it does not touch anything that is able to ground it. When u touch it, it does give u a pretty good shock though.

In computers, most things like motherboard, harddrive, optical drives, are grounded from their powersource so as long as the powersupply is grounded, hten you shouldn't have a problem.

A few things to keep in mind regarding ground:
1. The A/C source must be properly grounded.
2. The power supply provides ground to the case and/or MB tray, MB and I/O devices.
3. MB is grounded to the case (or MB tray).
4. The 0 volt reference is common to ground.
Finally, and most importantly as it relates to EMI, multi-layer MB's have an entire layer devoted to ground.

If EMI is a problem with any combination of case, power supply and MB then one or more of the components have failed or they do not meet FCC certification standards and should not be sold in the USA (the EU, and most of the world have a similar standard).

When you were building those devices, was is a case ground you were adding to the circuit, or was it a negative power supply connection? I would guess the later. The motherboard probably has an entire neutral layer and there are probably thousands of neutral points tied to that layer throughout the MB, which are not tied to chassis ground.

With that said, I would never personally build a machine in anything other than a metal case, but it's not because of overclocking ability or anything like that, but static, like 4ryan6 said too. I got in a discussion on the forums a while back and said that vacuum cleaners created static and I was nearly run out of town on a rail by an angry mob wielding torches and pitchforks.

Wood, generally speaking, will retain moisture and help to reduce/prevent static, at least to some degree, certainly more than acrylic. Wood will offer little protection for EMI though, same as acrylic.

cool cases. i made one case out of plywood when i was in vancouver. then put it on my balcony. it twisted into a potato chip - the humidity, i suppose. i took it inside & it un-twisted. had an MSI 845G with ultra-wide-SCSI 15 pound 47 GB seagate on it it.

i always wondered how the companies like the one that makes the Liquid XS in an acrylic case, get by the FCC.