Overclocking Via OC Dial
Besides ample multiplier and voltage adjustments in the BIOS, other “tweak–friendly” features of the 790FX-GD70 are the buttons and OC Dial located at the bottom of the board. The power and reset buttons are handy for those who run the board outside of a case, and just about any enthusiast can appreciate the recessed Clr CMOS button, rather than a conventional jumper. MSI’s OC Dial consists of the OC Drive knob and OC Gear button. These allow real-time adjustment to the reference clock.
The OC Dial function is enabled in the BIOS’s Cell menu. OC Dial Step increments can be increased if desired, but we used the default 1 MHz increments. OC Dial Value shows the changes made by turning the OC Drive knob. The Dial Adjusted Base Clock is the adjusted reference clock, and equals FSB Clock + OC Dial Value.
Again, we prepared the BIOS to overclock by lowering the NB and HT multiplier, as well as the memory ratio. OC Drive can be instantly adjusted while in the BIOS, but in the operating system the OC Gear button acts as an on/off switch. After pressing OC Gear for a second, the on-screen LED lights up and the OC Drive knob will then function. The knob has sixteen positions, allowing a reference clock increase of 16 MHz in one full rotation. Once adjustments are complete, pressing OC Gear again shuts down the feature, which we recommend to protect system stability.
We then began turning the OC Drive knob and watching the reference clock and frequencies change in CPU-Z. The system automatically rebooted after one of the changes. Upon entering the BIOS, we discovered that the crash occurred at the same 239 MHz reference clock that gave us trouble in AMD OverDrive.
After this minor hiccup, the system had no trouble booting into Windows at a 239 (200 + 39) MHz reference clock. We continued to increase the OC Dial value all the way to 65 MHz, the point where more voltage would then be needed to continue.
Voltages were increased and multipliers lowered. Back in Windows, we ratcheted up OC Dial in 10 MHz increments. The system crashed beyond a 286 MHz reference clock, and the OS failed to load if OC Dial Value was above 86 MHz.
After setting the CPU FSB frequency to 250 MHz, we rebooted back into the OS. This time the OC Dial could be increased all the way beyond our maximum fully stable overclock up to 288 MHz.