IntelDX4 is a clock-tripled i486 microprocessor with 16 KB level 1 cache.[1] Intel named it DX4 (rather than DX3) as a consequence of litigation with AMD over trademarks. The product was officially named 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 (3× 33.3 MHz). Both chips were released in March 1994. A version of 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 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. 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 3.3-V supply. Normal 80486 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 DX4 OverDrive CPUs have VRMs built in.
| Processor speed (MHz) | Input clock (MHz) and multiplier | Voltage (nominal) (V) | Voltage range (V) | Part number | Sspec number | |
|---|---|---|---|---|---|---|
| 75 | 25 × 3 | 3.3 | 3.1–3.6 | FC80486DX4-75 | SK052, SX883 | |
| 75 | 25 × 3 | 3.3 | 3.1–3.6 | A80486DX4-75 | SK047, SX884 | |
| 75 | 25 × 3 | 3.3 | 3.1–3.5 | A80486DX4WB-75 | SK102 | |
| 75 | 25 × 3 | 3.3 | 3.1–3.5 | FC80486DX4WB-75 | SK100 | |
| 100 | 33 × 3 | 3.3, 3.45 | 3.1–3.6 | FC80486DX4-100 | SX906 | |
| 100 | 33 × 3 | 3.45 | 3.3–3.6 | A80486DX4-100 | SK051, SX900 | |
| 100 | 33 × 3 | 3.45 | 3.3–3.6 | A80486DX4WB-100 | SK096 | |
| 100 | 33 × 3, 50 × 2 | 3.45 | 3.3–3.6 | FC80486DX4-100 | SX876 | |
| 100 | 33 × 3, 50 × 2 | 3.3, 3.45 | 3.1–3.6 | FC80486DX4-100 | SK053 | |
| 100 | 33 × 3, 50 × 2 | 3.45 | 3.3–3.6 | A80486DX4-100 | SX877 | |
| 100 | 33 × 3, 50 × 2 | 3.3 | 3.1–3.6 | A80486DX4-100 | SK050 | |
| 100 | 33 × 3, 50 × 2 | 3.3 | 3.1–3.6 | A80486DX4WB-100 | Limited availability | |
| 100 | 33 × 3, 50 × 2 | 3.3 | 3.1–3.6 | FC80486DX4WB-100 | SK099 |