Yes, you should ground at least one motherboard standoff to the PSU.  You can put an electrical ring terminal under a standoff and screw the standoff down to the motherboard tray so that it secures the ring terminal.  Then, run a wire from that ring terminal to another ring terminal which gets connected to the PSU.  For the ring terminal which you connect to the power supply, install a PSU mounting screw through it and into the PSU mounting hole.  That way, one of the motherboard mounting screws will be grounded to one of the PSU mounting screws.  The PSU case is grounded to the PSU internally.

You don't need to do that, the system will operate perfectly without any of the motherboard standoff's grounded.

I use a cardboard box as a platform for my motherboard to sit on for my overclocking bench and I've never encountered any grounding issues.

If you care about your computer and are worried about reducing the chance of failure due to static shock, you should ground it out.

bill1024
Normally there is no neutral on a 220 single phase or three phase. If it came off a sub panel the neutral is not bonded so you would need the ground. BX the jacket is grounded.
You should always hook up the ground wire and not bond neutral to ground at the fixture either.
But on the motherboard the screws have an isolation washer they give you to use, I see no connection on the bottom of the board where the mounting stands go.
 
 

And yes, of course you shouldn't use neutral as ground ... that was my point.  Just because they are both at the same potential and will function the same doesn't mean they fit the same purpose.  Just like the ground from the PSU through the EPS power plug and 24-pin plug don't fit the same purpose as the motherboard grounding.
 
anyways....
 
 
No, you are not supposed to use an "isolation washer" between your motherboard screws and standoffs.  I have never ever seen any instructions anywhere with any motherboard or chassis say to isolate the motherboard from the standoffs.  If you look at the motherboard mounting holes, you will see that the area around them doesn't have the mask over it.  In other words, the exposed copper is exposed on purpose.

They are just felt washers to give the screw head a better bite on the board to secure it. Much more necessary years ago, not as much now but most older builders will still use them.

Yes, it will work either way. I already agreed with that statement. I tried to provide some analogies to explain how "working" and being "proper" aren't always the same thing.

As stated, if you care about providing the most protection in the worst scenario, the motherboard should be grounded separately through the tray. Grounding the motherboard provides additional radio frequency and electromagnetic interference protection as well as providing additonal protection against damage due to static electricity. EMI, RF, and static care very little about individual grounds or small groups of grounds. Protecting against them requires more grounds and grounds distributed over larger areas. In the OP's case, he should ground at least one of the bottom standoffs the furthest away from the EPS and 24-pin plugs.

I feel like we are talking in circles. Do what you want. Either way works. One way is just better and is more true to the engineers' design. It is designed to be grounded separately and redundantly. If you don't care about adhering to the design, go ahead and do whatever you want. You can even make the ground circuit 110v above earth potential, if you want; just don't touch it.