Undervolting Your Phenom II And Core 2 Processors

Platforms: AMD 790FX And Intel P45

AMD/Socket AM3: MSI 790FX-GD70

We used MSI’s 790FX-GD70 to undervolt a Phenom II X4 955 processor. The board is MSI’s top model for Socket AM3, using AMD’s 790FX chipset with support for all the latest CPUs, ATI’s CrossFireX graphics technology (via four x16 PCI Express 2.0 slots), and lots of enthusiast-friendly features. The manufacturer implemented a hardware overclocking dial on the board, 4+1 voltage regulator phases with dynamic switching, and a large--but not excessive--heat pipe solution for the chipset and the voltage regulators. The BIOS allows you to set DDR3 memory speeds up to 2,133 MT/s. RAID is supported on all six 3 Gb/s SATA ports through the SB750 southbridge; more SATA ports, FireWire 400 and twin Gigabit LAN connections, plus 192 kHz HD audio are also available.

However, we hardly used any of these features this time, as the purpose of this project was to save power. The five-phase voltage regulator promises to be efficient, and the enthusiast-class board is equipped with quality components, which should support our ambitions. Still, we were a bit disappointed that it isn’t possible to adjust chipset or memory voltages downward. Maybe this is something MSI could add with a new BIOS release.

Intel/Socket LGA775: MSI P45D3 Neo

The Socket 775 motherboard we chose for the Core 2 Quad processor (we used a Core 2 Extreme QX9650) was the P45D3 Neo, which did a nice job on a recent overclocking project involving a Core 2 Duo. The board is based on the P45 chipset, but it’s not an enthusiast product: three voltage regulator phases have to suffice, there are no complex heat pipe solutions, and there are only few additions to the default chipset features. More information can be found in the article Overclocking Core 2 Duo: Power vs. Performance. Still, we decided to use this board, as other candidates we looked at for our undervolting projects—among them the Gigabyte X48T-DQ6, and an Asus P5Q Deluxe—also failed to offer substantial undervolting options for anything beyond the processor.