BIOS options and tweaking software
Nvidia has done an excellent job of getting all the little things right with its nForce 680i SLI reference board, and just as much attention has been paid to the BIOS.
While some motherboard makers shy away from overclocking, Nvidia has gone out of its way to ensure that the BIOS for its 680i reference board brims with powerful and easy to use overclocking options. Users can define quad-pumped front-side bus speeds between 400 and 2500MHz in 1MHz increments, which is finer granularity than what's offered by most BIOSes. The 680i SLI reference BIOS also offers fine-grain control over the memory bus, which can be set between an effective 400 and 1400MHz in 1MHz increments.
Rather than offering up a list of memory bus dividers, the nForce 680i SLI board's BIOS automatically picks a divider based on the target memory bus speed entered by the user. This approach is much more accessible for beginners who might not know exactly how bus divider math works, although those who don't probably shouldn't be overclocking.
Of course, you don't have to manually define the board's memory bus speed. The BIOS supports Enhanced Performance Profiles (EPP), so memory clock speeds will be set automatically when EPP-compatible modules are installed. EPP also provides the BIOS with information on optimal latency timings at various clock speeds, and you're free to tweak those timings further on your own.
Speaking of tweaking, the BIOS also offers access to some less common options, including multiplier control for Core 2 processors. You can't adjust the CPU multiplier up—that capability is reserved for Intel's "Extreme Edition" processors—but it is possible to push the multiplier down to as low as 6x. The BIOS also offers independent PCI Express bus speed control for each of its x16 slots, and a separate reference clock for the chipset interconnect.
On the voltage front, the BIOS serves up CPU voltages up to 1.8V in ultra-fine 0.00625V increments. Memory voltages are supported up to 2.5V, and voltage options are also available for the front-side bus, north and south bridge chips, and the HyperTransport interconnect. A complete list of voltage, multiplier, and bus speed options is available below.
| Bus speeds |
FSB: 400-2500MHz in 1MHz increments DRAM: 400-1400MHz in 1MHz increments PCIe x16 1: 100-200MHz in 1MHz increments PCIe x16 2: 100-200MHz in 1MHz increments PCIe x16 3: 100-200MHz in 1MHz increments SPP-MCP reference: 100-400MHz in 0.5-2MHz increments |
| Bus multipliers | CPU: 6x-10x (with Core 2 Duo E6700) MCP->SPP: 1x-5x SPP->MCP: 1x-5x |
| Voltages |
CPU: 0.5-1.8V in 0.00625V increments DDR: 1.8-2.5V in 0.025V increments MCH: 1.5-1.75V in 0.025V increments SPP: 1.2-1.55V in 0.05V increments HT: 1.2-1.55V in 0.05V increments CPU FSB: 1.2-1.5V in 0.1V increments |
| Monitoring | Voltage, fan status, and temperature monitoring |
| Automatic fan speed control | CPU, SYS |
| Manual fan speed control | North bridge, SYS2, AUX |
The above table splits fan speed control into two categories: automatic and manual. The former automatically adjusts fan speeds based on system temperatures, and is available for the board's CPU and system fan headers.
Temperature ranges and fan speed percentages can be defined for each of the automatic fan headers, allowing users to balance lower noise levels with adequate cooling. Ideally, we'd like to see this level of fan speed control applied to all onboard fan headers, but we'll take manual speed control over none at all. The board's remaining fan headers may not be smart enough to adjust fan speeds based on system temperatures, but it's nice to be able to arbitrarily throttle fan speeds through the BIOS.
Of course, it's even nicer to be able to do that in Windows. Nvidia has updated its nTune system utility to version 5.5 for the 680i's release, and the app packs a wide range of tweaking and overclocking options. Much of nTune's functionality relies on BIOS hooks that a surprising number of motherboard vendors fail to implement, but with Nvidia handling the BIOS for its nForce 680i SLI reference board, every nTune feature is supported in full.
In addition to providing a wealth of tweaking and overclocking options, nTune also provides control over more mundane functionality, such as the order of boot devices, and whether a full-screen logo is displayed at startup.
nTune's custom rules feature is a little more interesting, and allows users to configure system settings profiles that can be launched manually or in response to changes in system variables or active applications. Rules can be created that crank up clock speeds and voltages whenever a game is launched, and turn things down when the system is idling at the desktop or running a media player application. Warning tones and messages can also be set to respond to various stimuli, including system variables tracked by nTune's monitoring utility.
The nTune monitoring utility keeps tabs on system clock speeds, voltages, temperatures, and even fan speeds. Logging is also supported, making it easy to track things like system temperatures over time—a handy capability for anyone looking to tweak their system's cooling performance for lower noise levels or better performance.
Seeing nTune implemented in all its glory makes us wish Nvidia's board partners would do a better job of supporting the app. nTune is far better than any of the proprietary tweaking and overclocking utilities that mobo makers generally bundle with their boards, and it deserves more widespread support. Thankfully, motherboard makers who sign on to use Nvidia's reference design and BIOS should be assured full nTune functionality.
