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Five $160 To $240 990FX-Based Socket AM3+ Motherboards
BIOS Frequency, Voltage and Timings
 ASRock Fatal1ty
990FX Professional
Sabertooth 990FX
Reference Clock150-500 MHz (1 MHz)100-600 MHz (1 MHz)190-400 MHz (1 MHz)200-500 MHz (1 MHz)190-690 MHz (1 MHz)
CPU Multiplier8.0-31.5x (0.5x)4.0-35.0x (0.5x)2.5-23.5x (0.5x)7.0-35.0x (0.5x)4.0-32.5x (0.5x)
DRAM Data Rates800-1866 (266.6 MHz)800-2400 (266.6 MHz)667-1866 (266.6 MHz)667-1866 (266.6 MHz)800-1866 (266.6 MHz)
CPU Vcore0.60-2.00V (12.5 mV)0.68-2.08V (6.25 mV)+0 to +500 mV (50 mV)-0.06 to +0.60V (25mV)1.08-2.05V (~10.5 mV)
CPU NB0.60-2.00V (12.5 mV)0.50-1.90V (6.25 mV)Not Adjustable-0.06 to +0.60V (25mV)1.00-1.82V (~11mV)
990FX Voltage1.11-1.66V (10 mV)0.80-1.51V (6.25 mV)+0 to +500 mV (10 mV)0.87-1.98V (5 mV)0.96-1.39V (~5.5 mV)
DRAM Voltage1.25-2.07V (10 mV)1.20-2.50V (6.25 mV)-30 to +600 mV (10 mV)1.03-2.14V (5 mV)1.20-2.45V (~7 mV)
CAS Latency5-14 Cycles5-19 Cycles5-14 Cycles5-14 Cycles5-14 Cycles
tRCD5-19 Cycles2-19 Cycles5-19 Cycles2-19 Cycles2-19 Cycles
tRP5-19 Cycles2-19 Cycles5-19 Cycles2-19 Cycles2-19 Cycles
tRAS15-40 Cycles8-40 Cycles10-35 Cycles8-40 Cycles8-40 Cycles

All enthusiast-grade motherboards provide a wide enough range of voltage controls to fry our processor, and a wide-enough range of frequencies to make our processor completely unbootable, even before we have a chance to fry it. Yet, our tests target long-term stability, and that’s why we choose a maximum 1.40 V at the CPU core for our overclocking efforts.

Gigabyte leads Asus in maximum CPU overclock, but we still preferred overclocking with the Asus Sabertooth 990FX due to its ability to set a target voltage in firmware. The 990FXA-UD7 forces us to chase the appropriate voltage by increasing core offset and retesting until the desired voltage level is achieved.

ECS appears to beat ASRock, but we were not able to do this with firmware. Because AMD Turbo Core was always enabled, getting a consistent clock required the use of AMD Overdrive. We further had to make adjustments in Overdrive at every reboot, making the 4.30 GHz clock rate unacceptably cumbersome to use.

MSI’s low score was caused by voltage drop that resulted from MSI’s voltage compensation mechanism removed from its first AMD Bulldozer firmware.

The Sabertooth 990FX achieves the highest CPU reference clock, which is a setting that achieves its greatest significance when used to overcome the limits of locked multipliers (which, incidentally, none of the FX processors suffer from). MSI’s apparent misfortune is caused by boot failures whenever we attempted to manually lower its CPU-NB ratio, which climbed past the edge of stability in “Auto” mode as we pushed up the CPU base clock.

Asus must not have gotten the message that AMD’s FX has no DDR3-2133 ratio, as this is the setting it uses to achieve a class-leading DDR3-2205 data rate. Gigabyte forces us to make our push from the DDR3-1866 ratio by increasing reference clock, and both Gigabyte and MSI even drop that capability with four modules installed.

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