The IntelDX4 is a clock-tripled i486 microprocessor with 16 kB L1 cache. Intel named it DX4 (rather than DX3) as a consequence of litigation with AMD over trademarks. The product was officially named the IntelDX4, but OEMs continued using the i486 naming convention.
Intel produced IntelDX4s with two clock speed steppings: A 75 MHz version (3× 25 MHz multiplier), and a 100 MHz version (usually 3× 33.3 MHz, but sometimes also 2× 50 MHz). Both chips were released in March 1994. A version of the IntelDX4 featuring write-back cache was released in October 1994. The original write-through versions of the chip are marked with a laser embossed "&E", while the write-back enabled versions are marked "&EW". i486 OverDrive editions of the IntelDX4 had locked multipliers, and therefore can only run at 3× the external clock-speed. The 100 MHz model of the processor had an iCOMP rating of 435, while the 75 MHz processor had a rating of 319. The IntelDX4 was an OEM-only product, but the DX4 Overdrive could be purchased at a retail store.
The IntelDX4 microprocessor is mostly pin-compatible with the 80486, but requires a lower 3.3V supply. Normal 80486 and DX2 processors use a 5V supply; plugging a DX4 into an unmodified socket will destroy it. Motherboards lacking support for the 3.3V CPUs can sometimes make use of them using a voltage regulator (VRM) that fits between the socket and the CPU.
|Processor Speed (MHz)||Input Clock (MHz)||Voltage Center (V)||Voltage Range (V)||Part Number||Clock Multiplier||S-Spec Number|
|75||25 X 3||3.3||3.1 - 3.6||FC80486DX4-75||3X mode only||SK052, SX883|
|100||33 X 3||3.3, 3.45||3.1 - 3.6||FC80486DX4-100||3X mode only||SX906|
|100||33 X 3 / 50 X 2||3.45||3.3 - 3.6||FC80486DX4-100||3X or 2X mode||SX876|
|100||33 X 3 / 50 X 2||3.3, 3.45||3.1 - 3.6||FC80486DX4-100||3X or 2X mode||SK053|
|75||25 X 3||3.3||3.1 - 3.6||A80486DX4-75||3X mode only||SK047, SX884|
|100||33 X 3||3.45||3.3 - 3.6||A80486DX4-100||3X mode only||SK051, SX900|
|100||33 X 3 / 50 X 2||3.45||3.3 - 3.6||A80486DX4-100||3X or 2X mode||SX877|
|100||33 X 3 / 50 X 2||3.3||3.1 - 3.6||A80486DX4-100||3X or 2X mode||SK050|
|100||33 X 3||3.45||3.3 - 3.6||A80486DX4WB-100||3X mode only||SK096|
|100||33 X 3 / 50 X 2||3.3||3.1 - 3.6||A80486DX4WB-100||3X or 2X mode||Limited availability|
|75||25 X 3||3.3||3.1 - 3.5||A80486DX4WB-75||3X mode only||SK102|
|100||33 X 3 / 50 X 2||3.3||3.1 - 3.6||FC80486DX4WB-100||3X or 2X mode||SK099|
|75||25 X 3||3.3||3.1 - 3.5||FC80486DX4WB-75||3X mode only||SK100|
- http://www.olympusmicro.com/micd/galleries/chips/pages/intel486dx4a.html — photomicrograph of a DX4 microprocessor