VOLTAGE REGULATING MODULE
A component required to drop the 5 volt power on the motherboard to the 3 to 4 volts or less required by many 486DX2 and later CPUs. VRMs use heat generating variable resistance techniques. They may generate nearly as much heat as the CPU -- in a smaller physical area. They can run very hot. Maximum VRM temperatures should not exceed 75C at the junction -- about 70C at the case. Most VRMs include thermal shutdown features which will cause the computer to stop mysteriously if the VRM gets too hot. In some cases plug in replacement CPUs may require replacement of the VRM or improved cooling (bigger heatsink/fan) because of voltage differences or higher current requirements at the same voltage. When replacing VRMs attention must be paid to the current capacity at low voltage drops because some VRM devices can't drop rated currents at low voltages.
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Copyright 1994-2002 by Donald Kenney.