AB-PB4 © 199? Abit
The Abit AB-PB4 is the performance-oriented flagship of the Abit P-series. Built upon the ALi (Acer Laboratories Inc.) M1489/M1487 chipset (the "FinALi" architecture), it is widely considered the best platform for maximizing the performance of late-era 486 and "5x86" processors.
Chipset: ALi M1489 / M1487 ("FinALi-486").
CPU Support: Socket 3. Supports Intel 486SX/DX/DX2/DX4, AMD Am486, Am5x86-P75, and Cyrix 5x86.
Expansion: 3x PCI slots, 4x ISA slots.
Memory: 4x 72-pin SIMM sockets (EDO DRAM supported).
Form Factor: Baby AT.
Cache: 256KB/512KB L2 cache (DIP-socketed).
The "5x86" Benchmark: The AB-PB4 is legendary among retro-enthusiasts as the "Gold Standard" for the AMD Am5x86-P75. The ALi chipset allowed for aggressive memory timing adjustments that other chipsets (like the SiS 496/497) could not maintain, often allowing this board to outperform the AB-PV4 in integer-heavy DOS benchmarks.
Jumper Flexibility: This board was a dream for early "overclockers." The jumper table printed on the board allowed for precise voltage adjustments (3.3V, 3.45V, 3.6V, 4V, 5V), which was essential for pushing the early 3.3V processors without burning them out.