BIOS And Overclocking

The Ai Tweaker menu contains enough settings to take up three screens. The first screen includes settings for automatic (Ai) overclocking, manual FSB clock speed, PCI Express frequency, DRAM ratio, DRAM skew controls and basic DRAM timings.

Ai Overclocking supports fixed, variable and manual overclocking modes. Fixed mode settings range from 5-20% in 5% increments, while variable "N.O.S." modes of 3%, 5%, 8% or 10% dynamically change CPU clock frequencies in response to high workload conditions.

The FSB is adjustable from 200 to 800 MHz (FSB-800 to FSB-3200) in manual overclocking mode, though we’ve rarely seen even the most extreme overclockers go much beyond 600 MHz FSB clock on any chipset. Likewise, PCI Express clock is adjustable between 100 and 180 MHz, even though 150 MHz is considered by many overclockers to be a practical limit, and several have reported southbridge malfunctions at far lower settings. Frequency settings in excess of practical limits exist to challenge the best overclockers to reach beyond expectations in their competitive efforts.

All eight standard Intel DRAM ratios are available, and are dependent on FSB bootstrap, but leaving the FSB strap to "Auto" opens up the full range of options while letting BIOS chose the most appropriate bootstrap. Additionally, Asus offers DDR3-1800 and DDR3-2000 settings, which the board achieves by lowering the CPU multiplier and raising its FSB to either 450 or 500 MHz. Those options disappear whenever the FSB is manually set.

The second Ai Tweaker screen contains advanced DRAM timings.

A wide range of timings for each setting meets or exceeds the capabilities of Intel’s memory controller, tempting the most enthusiastic "tweakers" to try ever-better RAM in the pursuit of world-leading performance.

The third Ai Tweaker screen contains all-important voltage controls, plus spread spectrum, voltage calibration, and clock skew settings.

CPU core voltage is adjustable from 0.850 to 2.100 V in tiny 6.25 millivolt increments. Using 1.60 V CPU core and 1.50 V FSB termination on a Core 2 Duo E6850, we were able to reach 535 MHz FSB (FSB-2140) at a 6x CPU core multiplier, and 4.01 GHz CPU clock speed at the processor’s default 9x multiplier.