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Roundup: Four 790FX Socket AM3 Motherboards

Overclocking, Power, And Heat

All of the motherboards in today’s comparison provide frequency ranges that exceed by far any realistic expectations of stability and most voltage ceilings are far beyond any realistic expectations of reliability. Experienced overclockers know not to shoot for the limit at first, but instead determine the maximum supported speed and required voltage by making small changes and retesting repeatedly.

BIOS Frequency And Voltage Settings (For Overclocking)
 Asus M4A79T DeluxeDFI LANParty DK 790FXB-M3H5Gigabyte MA790FXT-UD5PMSI 790FX-GD70
CPU Ref Clock200-600 MHz (1 MHz)200-700 MHz (1 MHz)200-500 MHz (1 MHz)200-600 MHz (1 MHz)
CPU MultiplierYesYesYesYes
DRAM Data Rates800/1066/1333/1600800/1066/1333/1600800/1066/1333/1600800/1066/1333/1600
PCIe Clock100-150 MHz (1 MHz)100-250 MHz (1 MHz)100-200 MHz (1 MHz)100-150 MHz (1 MHz)
CPU Vcore0.80-1.70V (0.0125V)-800-+775mv (25mv)+25-600mV (25mV)0.98-1.93V (0.01V)
IMC Voltage0.80-1.55V (0.0125V)+3.57, 7.14, 10.71%+25-600mV (25mV)0.85-1.83V (0.01V)
790FX Core1.10-1.40V (0.02V)1.12-1.50V (0.04V)+0.1, +0.2, +0.3 V0.75-1.83V (0.01V)
SB750 Core1.20-1.35V (0.15V)1.20-1.50V (0.20V)+0.1, +0.2, +0.3 V0.85-1.83V (0.01V)
DRAM Voltage1.50-2.50V (0.02V)1.50-2.49V (0.22V)+50-750mV (50mV)1.19-2.40V (0.01V)
CAS Latency4-12 Cycles4-11 Cycles4-12 Cycles4-12 Cycles
RAS To CAS Delay5-12 Cycles5-11 Cycles5-12 Cycles5-12 Cycles
Row Precharge5-12 Cycles5-11 Cycles5-12 Cycles5-12 Cycles
tRAS15-30 Cycles16-30 Cycles15-30 Cycles15-30 Cycles

The two boards with the “smallest” CPU voltage regulators also have the most aggressive voltage levels, but we limited our CPU core to 1.45 V to assure longevity.

The two motherboards with 10-phase power regulation finished first and last, with Gigabyte providing the highest stable CPU clock at our chosen voltage levels.

MSI has the best reference clock stability. A combination of first-place reference clock and second-place CPU stability could make the 790FX-GD70 a top overclocking choice for multiplier-locked processors.

Dropping timings all the way back to 9-9-9-28 at 2T wasn’t enough to get most configurations beyond DDR3-1600, though Asus did break that barrier with four modules installed.

The two five-phase power regulators placed first and last in thermal performance. MSI’s win is probably due to its enormous VRM sink.

All of today’s motherboards appear energy efficient, yet none stand apart. Chipset and CPU manufacturer AMD gets all the credit for an overall good showing.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.