Intel i486 SX 25MHz CPU A80486SX-25 SX790 Socket 1/2/3 486 Processor

Intel i486 SX 25MHz CPU A80486SX-25 SX790 Socket 1/2/3 486 Processor

The Intel A80486SX-25 is a 25 MHz i486 SX processor — the math-coprocessor-free variant of Intel's 80486 CPU family. Marked with stepping SX790 and manufactured in Malaysia (per the underside label dated 1989/1992), this is a fully functional 32-bit x86 processor in a 168-pin ceramic PGA package.

Specifications & What's Included

• Manufacturer: Intel
• Part Number: A80486SX-25
• Stepping: SX790
• Clock Speed: 25 MHz
• Architecture: 32-bit x86 (80486)
• FPU: None — SX variant (no built-in floating-point unit; compatible with separate 487 math coprocessor)
• Package: 168-pin ceramic PGA
• Socket Compatibility: Socket 1, Socket 2, Socket 3
• Bus Speed: 25 MHz
• Country of Manufacture: Malaysia
• Underside assembly code: 93341756AC
• Intel copyright date: 1989/1992
• Included: CPU only — no socket, cooler, or accessories

Applications

The Intel 486 SX was introduced in 1991 as a lower-cost alternative to the full 486 DX, differing only in the absence of a built-in floating-point unit. It was used in a wide range of early 1990s desktop and tower PCs running MS-DOS and early Windows (3.0, 3.1, and early Windows 95 systems). Socket 1/2/3 boards accepting the 486 SX were produced by manufacturers including ASUS, Gigabyte, and numerous OEMs through the early-to-mid 1990s. Today these processors are sought by vintage PC enthusiasts restoring period-correct 486-class machines, as well as collectors interested in early Intel CPU history. The SX variant could be paired with an Intel 487SX math coprocessor to restore floating-point capability, making it a flexible choice for motherboards with a co-processor socket. The 25 MHz speed bin represents the baseline tier of the 486 SX line, sitting below the 33 MHz and 40 MHz variants.