BIOS and tweaking software
Unsurprisingly, the C51XEM2AA and M2N32-SLI have a lot in common when it comes to BIOS-level tweaking and overclocking options. Both boards give users access to nearly every memory timing option under the sun, including support for the Enhanced Performance Profiles found in newer DDR2 modules. Unfortunately, though, neither provides much control over the memory clock speed. Users can lock memory speeds below DDR2-400, 533, 667, and 800, but aren't given control over specific multipliers for manual fine-tuning.

On the overclocking front, the M2N32-SLI offers a little more granularity, allowing for HyperTransport clock speeds between 200 and 425MHz in 1MHz increments. The C51XEM2AA, on the other hand, allows for an HT clock between 100 and 500MHz, but only in 2MHz increments. Overvolting favors the C51XEM2AA. The Foxconn supports CPU voltages as high as 1.85V, while the M2N32-SLI's CPU voltage tops out at 1.5625V.

As a part of their support of Enhanced Performance Profiles, both BIOSes have a set of "SLI-Ready Memory" overclocking options. These options automatically overclock a system's memory as far as possible while keeping the CPU at its stock speed. Users can also allow the automatic memory overclocking to increase the CPU clock by between 1 and 14% to achieve higher memory speeds.

So both BIOSes pay plenty of attention to overclocking options, but only the M2N32-SLI offers BIOS-level fan speed control. Users can choose between a few different fan speed profiles for the board's CPU and system fan headers, although it isn't possible to dial in target temperatures or to directly manipulate fan voltages. Still, it's better than the Foxconn's utter lack of fan speed control.

While hardly a killer feature, the M2N32-SLI's BIOS also sports an alarm clock that will wake you up with music from a CD in the system's optical drive. I can think of a few things I'd rather see in the BIOS than an alarm clock, such as control over the max Cool'n'Quiet CPU multiplier to allow clock throttling to cooperate with overclocking, or more extensive control over temperature triggers and voltages for onboard fan headers. But the alarm clock is at least novel. The M2N32-SLI is also capable of saving two different BIOS profiles, each with its own unique set of tweaking and overclocking settings.

Most enthusiasts are more than happy to do their motherboard tweaking in the BIOS, but NVIDIA has whipped up an all-new version of its nTune system utility for the nForce 590 SLI. This new utility offers an extensive array of tweaking, overclocking, and hardware monitoring options, all of which are supported by both the C51XEM2AA and M2N32-SLI.

nTune's monitoring panel

Motherboard options galore

Few motherboard manufacturers provided the BIOS hooks necessary to exploit all of the features offered by older versions of nTune, but it looks like NVIDIA's done a better job of evangelizing the app for the nForce 590 SLI. nTune's most recent release is much smarter than previous versions, as well.

The app now features a rules wizard that allows users to create system settings profiles that are automatically invoked when applications launch or stop, when system temperatures change, or in response to other stimuli. Rules aren't limited to switching nTune profiles, either; they can also be used to display warning messages or to launch third-party applications.

nTune is all that's available to tweak and monitor the C51XEM2AA from Windows, but Asus also includes its own suite of Windows apps with the M2N32-SLI. PC Probe and AI Booster both make an appearance, although neither is as slick as the latest version of nTune, which NVIDIA provides free of charge.