Topic summary
486 DX4
Extracted from the Wikipedia article Intel DX4.
The IntelDX4 microprocessor is mostly pin-compatible with the i486, but requires a lower 3.3-V supply. Normal i486DX and DX2 processors use a 5-V supply; plugging a DX4 into an unmodified socket will destroy the processor. Motherboards lacking support for the 3.3-V CPUs can sometimes make use of them using a voltage regulator module (VRM) that fits between the socket and the CPU. The i486 DX4 OverDrive CPUs have voltage regulator modules built in.