Just to correct this bit of misinformation, despite it being three years old, you are ILL advised by anybody who tells you it is ok to only use SOME of the 9 standoffs that are SPECIFICALLY intended to be used on ATX motherboards.
There is no "circuitry" around ANY motherboard standoff hole, ever. Ever, ever, ever, ever, ever.
The metal you see around standoff holes is NOT there for grounding, or any electrical purpose of any kind. That is ONLY there as reinforcement so that the upward and downward force of the standoff and fastener do not crush the PCB material. That's it, and that's all. Period.
As far as not using all of the standoffs, for anybody who happens to wander by and read the best answer saying it's ok to use only six, I advise against that, and recommend that you ALWAYS use all of the standoffs. If you don't HAVE enough, GET them, and make sure they are the same height and thread pitch as the ones you already have. Leaving off standoffs can cause SERIOUS damage to the motherboard, by allow flexion to crack traces, solder points, damage contacts and so on. Also, always make sure that you ONLY use standoffs in the locations where there is a matching standoff hole in the motherboard. Otherwise, you will likely short out or otherwise damage the motherboard as well.