Overclocking

Now that we’ve become acquainted with the mainboard, it’s time to see what it can do at practical overclocking. To perform our experiments, we built a system with a DFI Infinity 975X/G, a Core 2 Duo E6300 CPU (its default clock rate is 1.86GHz), 2GB of DDR2 SDRAM (Corsair TWIN2X2048-8500C5), a PowerColor X1900 XTX 512MB graphics card, and a Western Digital WD1500AHFD hard disk drive. The i975X chipset often fails to work properly at memory frequencies of near 1GHz, so we set the biggest DDR2 frequency divisor of 4:3 for the time of our tests. The CPU was cooled with a Zalman CNPS9500 LED.

First we wanted to see what FSB frequency we could reach without changing the North Bridge voltage. It was quite predictable: at a FSB clock rate of 412MHz the mainboard is perfectly stable even at 1.6V on the chipset.

Like with other i975X-based mainboards, you can increase the FSB frequency higher by lifting up the voltage on the chipset’s North Bride first. The higher the voltage, the better results you can expect to achieve. The DFI Infinity 975X/G confirmed our point: the maximum of FSB frequency moved up to 451MHz after our setting 1.75V on the North Bridge.

This is quite a normal result for an i975X-based mainboard. Better overclocking can be achieved on those mainboards that allow setting a higher voltage on the chipset. Well, if 450MHz is too low for you, you can try to overclock your Infinity 975X/G using a volt-mod. Some overclockers have reported on the Web that they have conquered FSB frequencies above 500MHz on the Infinity 975X/G.

In our experiments we managed to overclock our Core 2 Duo E6300 to 3.15GHz. We achieved this by slightly increasing the CPU voltage, 0.1V above the default value. This indicates that the mainboard didn’t allow to reveal the full overclocking potential of the CPU. So, we can’t call the Infinity 975X/G an ideal platform for overclocking junior CPU models from the Core 2 Duo E6000 series.

The mainboard should do better with CPUs that have a bigger multiplier, but this is not always the case in practice. Our experiments on overclocking an engineering sample of the not-yet-announced Core 2 Duo E4300, expected to work with a 9x multiplier and a 200MHz FSB, were a fiasco.

Strangely enough, the highest FSB frequency the Infinity 975X/G was able to work with that CPU at was only 295MHz. That’s obviously not the limit for the CPU, yet the mainboard refused to pass the POST at higher FSB frequencies. So, there is clearly some incomplete compatibility of the mainboard’s BIOS with Core 2 processors that work with a 200MHz FSB by default. But considering DFI’s meticulous approach to supporting its own products, we hope this problem will soon get a solution.