Not sure if this is the right category for this question...
Or if this is a stupid question or not...
Im thinking about building a case out of wood. I googled the subject and I havent found anywhere that says the motherboard HAS to be grounded and on a metal motherboard tray. I was just going to drill holes and screw the standoffs into the wood and slap the mobo on that way. I figured it would be grounded by the psu.
BUT every wooden case mod I have looked at online seems to be using another cases mobo tray or a DIY mobo tray from somewhere. Is that really necessary? Or can I just attach all the components to the wood itself without problems?
You could just run an earthing cable from a mobo mounting hole to the psu casing only risk is if the psu went, it could send a current down to the mobo, but that could happen via the power cable. I wouldn't worry, give it a good test using old parts that you wouldn't miss if things go wrong.
no grounding necessary. Go ahead and build it as you like. The PSU is grounded anyways via it's power cable.
The reason cases are built out of metal is because the case itself can take some of the heat from inside and radiate it, hence helping cooling. Also, when serviced, if someone grounds himself to the case, reduces the odds of causing an electrical charge and zapping the mobo. Other than that, no issues.