Thomas Mayer wrote: > Dean > > ESD can vary between 200 volts and 2,000 volts. If the computer case is > not grounded, there is a risk that the charge could reach some internal > electronic computer components before dissipating into the atmosphere. > And, once the power supply itself is turned off, there is no electricity > reaching the internals, but the remaining connection to a grounded > outlet provides a ground for the case. Of course working in the power > supply itself is an exception. There are even specially designed computer cords (usually colored in a primary color) that only connect the ground plug to the AC outlet. http://www.cyberguys.com/templates/searchdetail.asp?productID=5338 http://www.cyberguys.com/templates/searchdetail.asp?productID=5339 The main reason I recommend users unplug is that not all power-supplies have a disconnect switch on the back of the PSU. Also, not all ATX motherboards include a "power LED" that shows whether the motherboard is still receiving power from the PSU. (Different approaches and different valuations of risks. I had one user swapping memory on a live ATX system because they didn't understand that just because a unit is powered off doesn't mean there's still juice on the motherboard. Fortunately, it did no damage. But the system was in a very confused state and would not power back on until I cut the power by pulling the plug for 30 sec.) Visit our website regularly for FAQs, articles, how-to's, tech tips and much more http://freepctech.com