Basically, the powerstrip does not have the type of circuitry that can arrest the over voltage. With real surge protectors you get more circuitry that will stop the electrical surge from going past the suppressor stage. With the simple versions you have to blow a simple fuse, which has too wide a range of tolerances as far as how much voltage it will let through. This can lead to problems when it comes to the delicate circuits that a typical computer has. Too much voltage, even a relatively tiny variation, can cause major trouble. It is always best to go with a high end surge suppressor or a combination UPS/surge protector (I've even used the version that will protect against brown outs).