4DMU HL3S © 199? EFA Corp.
The 4DMU HL3S was a workhorse board that prioritized compatibility over the "tweaker" features found on high-end boards like the Abit series. It utilized the UMC (United Microelectronics Corporation) UM8498F chipset, similar to the Abit AB-PM4, but implemented it with a more conservative, integrated layout intended for general office use rather than the enthusiast "performance" market.
Chipset: UMC UM8498F / UM8496F.
CPU Support: Socket 3. Compatible with Intel 486DX/DX2/DX4 and the AMD Am486 series.
Expansion: 3x PCI slots / 4x ISA slots.
Memory: 4x 72-pin SIMM sockets (typically FPM support).
Form Factor: Baby AT.
Cache: 256KB of L2 cache (usually DIP-socketed).
The UMC Implementer: While your Abit AB-PM4 is the "performance" king of the UMC chipset boards, the EFA 4DMU is the "stability" counterpart. EFA motherboards were frequently rebranded and sold inside complete "white-box" PC systems. If you have an unlabeled generic 486 PC from 1995, there is a very high probability that an EFA 4DMU is under the hood.