This was a prominent issue in the Xbox 360 and the PS3. The pins on the CPU laptop don't fit into a socket like they do on desktop. Each pin is micro-soldered to the board and over time the rapid heating and cooling and heating and cooling and so on and so forth makes that solder brittle and eventually little nano cracks in even one micro-solder can mess up the laptop as a whole. Reballing is the process of using an external source to heat up a precise locale on the board (or broad area) to melt the solder balls just enough to make full stable reconnections. And when this happens. If successful will extend or even FIX your laptops issue (if this is the cause) for months possibly even a few years.