by Karlsweldt » Tue Dec 14, 2004 6:47 am
There is an electrical phenomenon known as a "ground loop" which can play havoc with electrical circuits. It works the same way as a solid loop of wire in an electromagnetic field. Pass a loop of wire that is connected, such as a large metal ring, through a magnetic field. You will feel some unseen forces working on it. That is how the power meter works at your home. Induced magnetic fields cause an aluminum disk to rotate. Power is induced in the loop, and heating is produced, as well as shunting certain radio frequencies. The motherboard is grounded mainly through the power connector. There are additional ground points, such as the "fingers" that contact the keyboard/mouse and port sockets. Plus several of the solder pads for mounting of the mobo. Consider the setup of a motherboard the same as using a power tool on an extension cord. It has the two power leads, and a ground lead for safety. Works very well. All the black wires are both ground and return leads. Only the black wires are connected inside the PSU to the case, which in turn is connected to the power source ground. Having more than one source of ground can lead to disturbing erratic electrical signals, and strange behaviour of the equipment. That is one reason it is good sense to have all computer equipment on one branch circuit, having the same ground source. Prevents the small voltage/high current inducements from forming by the "ground loop" theorum. The electrical tool called the "Amprobe" works on this principle, to detect current flow without cutting into the circuit. There are complicated formulas in the electrical field. Having diferent lengths of wire in a constant flux field cause differing curent/voltage results.
Hope my post was not too confusing. Perhaps too high-tech.
Just consider that having the mobo out of the case and off its mounts will allow it to work properly, with only the grounding of the power connector. Many mobos of years gone by had many grounding points. They also experienced power and signal problems. Today, the shortest single path from the source to the demand is the best. Alternate paths of return can create problems.