Zero Insertion Force - A term used for certain CPU sockets that accept the CPU into the board without any downward pressure. CPU's such as the Athlon and Duron will just drop into the slot and a lever will secure them. The older slot CPU's required a small amount of force to insert them into the slot. If you finding yourself pushing down on a CPU in a ZIF socket then you are likely to have the CPU incorrectly position and may damage the CPU.