AB-PW4 © 1995 Abit
The Abit AB-PB4 is a well-known Socket 3 motherboard from 1995, frequently sought after by retro-computing enthusiasts for building high-end 486 or "5x86" (Am5x86) systems.
Chipset: ALi M1489/M1487 (also known as the "FinALi-486 PCI" chipset).
CPU Support: Socket 3 (supports 486SX, DX, DX2, DX4, and the AMD Am5x86-P75).
Expansion: 3x PCI slots and 4x ISA slots.
Memory: Typically 2x or 4x 72-pin SIMM sockets supporting EDO DRAM (up to 64MB or 128MB depending on the revision).
Form Factor: Baby AT.
Cache: Usually features 256KB of L2 cache (often in DIP sockets, allowing for upgrades to 512KB).
The ALi Difference: While your collection is heavy on SiS and UMC chipsets, the ALi (Acer Laboratories Inc.) M1489 chipset on the PB4 is prized for being very stable and quite fast for late-era 486 builds.
The Am5x86 Sweet Spot: This board is famous in the retro community as one of the best platforms for the AMD Am5x86-P75, which was the absolute performance ceiling for the 486 architecture. If you are looking to maximize a 486 system, this board is frequently the top recommendation.