This item is from the PC Hardware FAQ, by Willie Lim and Ralph Valentino with numerous contributions by others. (v1.25).
[From: jabram@ichips.intel.com (Jeff Abramson)]
ZIF stands for Zero Insertion Force, and describes a socket on your motherboard that supports an upgrade processor (overdrive processor). In general, an overdrive upgrade works in conjunction with your original processor so you cannot remove the original processor after upgrade. NOTE: Some motherboards do not have a ZIF socket so you must replace the existing processor to upgrade.
 
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