MSI P55A-GD65 Motherboard

Voltage Regulator

The MSI P55A-GD65 comes with a high-end voltage regulator circuit called DrMOS, with a total of ten phases, eight for the CPU (Vcore) and two for the integrated memory controller (VTT rail).

Each phase doesn’t use discrete MOSFET transistors, but integrated circuits containing these transistors. Each “DrMOS” chip (Fairchild FDMF6704V) features three MOSFETs inside (“high side,” “low side,” and the driver) switching at 1 MHz, instead of the 250 kHz of traditional voltage regulators, in order to increase efficiency (i.e., less energy is wasted, causing the CPU and memory to pull less energy from the power supply compared to other designs). According to MSI one “DrMOS” phase is more efficient than four traditional phases because of that design. The manufacturer promises efficiency up to 96%, an increase of 38% over the traditional design.

This motherboard comes with a passive heatsink on top of only four of those integrated circuits. The removal of one of the heatsinks and the heatpipe was one way the manufacturer found to reduce costs, reducing the motherboard price.

All capacitors used on the voltage regulator circuit and on the rest of the motherboard are solid and all chokes are ferrite models, which are better than iron chokes.

Please read our Everything You Need to Know About the Motherboard Voltage Regulator tutorial for more information.

Figure 6: Voltage regulator circuit

Figure 7: Close-up of the voltage regulator circuit

Besides having a high-end voltage regulator circuit, the P55A-GD65 can disable phases from the voltage regulator circuit as needed in order to save energy, a feature called APS (Active Phase Switching). A group of LED’s near the memory sockets indicate how many phases are active at any given moment.