Sorry to hear of your delima...is it possible that the mobo's are being mishandled by your supplier....were the mobo's still in their sealed anti-stat packaging. Are all these computers hooked up to a surge suppressor, and/or properly grounded. And, are you atempting (or those using the computers) pluging in or out the usb devices while the computer is on. Usually Asus will tell you what was wrong with the mobo's you turned in for repair.