Chip creep
Chip creep refers to the problem of an integrated circuit (chip) which, over time, would work its way out of the socket; this was mainly an issue in early PCs.
Chip creep occurs due to thermal expansion; the contracting and expanding during system heat up and cools down. While chip creep was most common with older memory modules it was a problem with other main chips (or CPUs) that were inserted into sockets.