Loongson 3B1500 (LS3C-2WAY-SERVER) Motherboard

Loongson 3B1500 Dual Development board (龙芯3B1500双路开发板 [archive.org]) uses two Loongson 3B1500 processors and AMD RS780E+SB710 chipset. The board is also referred to as 龙芯3B05+RS780E双路开发板 in newer documents. Loongson is a series of system that are designed in China. GODSON is the academic name for the Loongson processors. This family of processor implements MIPS instruction set [1].
LS3C-2WAY-SERVER V1.0 Loongson motherboard Loongson LS3C-2WAY-SERVER pin side backpanel DDR3 modules

The motherboard has standard Extended ATX (E-ATX) mounting holes and can be installed in commodity PC chassis. I like how they keep unnecessary costs down this way. I went one step further and installed it in an ATX chassis (Corsair Carbide 400Q) with smaller number of mounting screws. So far it's working, but I cannot recommend anyone else to do the same.

The sticker on DIMM says HXMSH8GP13A1F1V-13H 8GB, 2RX8, PC3-10600P-999. These memory modules appear to be standard DDR3-1333 1.35V/1.5V Registered ECC DIMMs.


The firmware is called PMON2000. It has both CLI and BIOS Setup-like menu. The Loongson BIOS Setup says that the processor is GODSON3 @ 1000 MHz. While the BIOS Setup only recognizes 16 GBytes of memory on the first node, the Linux kernel recognizes the full 32 GBytes of memory.
Loongson BIOS Setuo PMON CLI

The firmware refused to load any kernel saying attempt to load into mappable region until we updated the PMON to latest build of 3.3. Latest firmware for this board is found on 3B780E1500双路开发板 [loongnix.org]. PMON update procedure is found on PMON编译方法 [loongnix.org].

Operating System

The Loongson Linux is found on Loongnix系统 [loongnix.org]. The Fedora21-MATE 20150815-Release works fine on this board.

As seen on the diagnostics messages above, only 15 processor cores are available to the user. The motherboard is a two-socket system, so it is odd to have an odd CPU count (naturally).

Installation Notes

There were following issues when installing Fedora-MATE-Live-5.iso image on 2017-Jan-07.


  1. W. Hu, L. Yang, B. Fan, H. Wang and Y. Chen, An 8-Core MIPS-Compatible Processor in 32/28 nm Bulk CMOS, in IEEE Journal of Solid-State Circuits, vol. 49, no. 1, pp. 41–49, Jan. 2014.