It the luck of the draw when it come in prebuild machine from any large manufacturing personal PC company (Dell, HP, Acer, etc). I've work on and personally use most of the name brand PC builder in the past and now. You have to remember when large PC company built there system, they get parts from different vendors as well, those vendors parts come in new, will be defective sometime at a different rate in their life span. Computer parts come in from cheaply made to high-end parts, high-end parts do get DOA sometime too. Even when you built a machine yourself, you don't know if it work as advertise, until you power it up and use day by day. And then their the end user, how they use it and if it maintain properly or what the environment the PC place. I can compare PC to car. If you don't do maintenance, it not going to last, but some you beat it up it still last, because of the right parts, go figure.