MSI 990FXA-GD80 Motherboard

Voltage Regulator

The CPU voltage regulator circuit of the 990FXA-GD80 has eight phases for the CPU main voltage (VDD a.k.a. Vcore) and two for the CPU VDDNB voltage (integrated memory controller, HyperTransport bus controller, and L3 memory cache). Therefore, it uses an “8+2” configuration.

Figure 8: Voltage regulator circuit

Figure 9: Voltage regulator circuit

This motherboard uses military-class components. Electronic components are available in two series, civilian and military. Military components are more expensive but have tighter tolerance and can withstand a wider range of temperatures. All electrolytic capacitors used in the main voltage regulator circuit are SMD (surface mount device), also known as highly-conductive polymerized or simply Hi-c, but the other voltage regulators (memory, chipset, etc.) use solid capacitors. All coils on this motherboard are solid ferrite-core models, also known as SFC, Super Ferrite Choke, which, according to MSI, can provide up to 20% improvement in efficiency.

Each main phase is controlled by a Fairchild FDMF6704 integrated circuit, which combines the three required transistors (“high side,” “low side,” and “driver”) in a single chip. It also allows the switching clock to be at 1 MHz, which allows efficiency to be over 90 percent. (Usually, voltage regulator circuits switch at 250 kHz.) Integrated circuits with those characteristics are known as “DrMOS.”

If you want to learn more about the voltage regulator circuit, please read our tutorial on the subject.

The motherboard has two LEDs for you to monitor the active VDDNB phases, eight LEDs for you to monitor the active main CPU voltage phases, and two LEDs for you to monitor the active memory voltage phases.

Figure 10: Phase-monitoring LEDs