Compared with the previous Gigabyte solutions from DQ6 series, GA-X38-DQ6 has quite a few changes that should make it more overclocking friendly. The mainboard cooling system is compatible with most processor coolers, the BIOS Setup has no hidden sections, and system monitoring displays the numeric voltage values. All this is clear indication that Gigabyte developers started taking overclocking fans much more seriously.
To check out the overclocking potential of the Gigabyte GA-X38-DQ6 mainboard, we assembled a special testbed including the following equipment besides the board itself: 2GB DDR2 from Corsair (Dominator TWIN2X2048-10000C5D), OCZ GeForce 8800GTX graphics card, Western Digital Raptor WD1500AHFD HDD and SilverStone SST-ST85ZF power supply unit. We used a Scythe Infinity processor cooler, too.
First of all we decided to determine the maximum FSB frequency when the board would remain stable and reliable with a dual-core processor. We used a Core 2 Duo E6750 processor. For stability check we ran Prime95 25.3 program for 30 minutes in Large FFT and Blend modes.
We encountered no problems here: the mainboard worked fine at FSB speeds beyond 500MHz. By raising the North Bridge voltage 0.15V above the nominal we got the system to run stably at 520MHz FSB. And the increase in the North Bridge voltage by 0.175V pushed our test processor to 525MHz FSB that is its FSB Wall.
The memory was clocked synchronously with FSB in this case and functioned at 1050MHz with 4-4-4-12 timings.
Note that it was very simple to overclock our CPU in this case. To obtain the above mentioned result we didn’t have to try all sorts of settings. All voltages except processor Vcore, Vmem and North Bridge voltage were set to Auto.
The second overclocking experiment was performed on a quad-core Core 2 Extreme QX6850 processor. These CPUs are known to overclock a little worse on the FSB side than their dual-core counterparts.
As soon as the FSB frequency reached 450MHz, we had to increase the chipset North Bridge voltage by 0.1 to ensure system stability. Further FSB frequency increase was only possible with dramatic growth of this voltage. For example, at 465MHz FSB the chipset North Bridge voltage had to be raised by 0.3V, otherwise the system stability was questionable. By the way, at the same time we had to increase the FSB voltage by 0.1V, too.
The maximum FSB frequency when our mainboard remained stable with a quad-core processor equaled 475MHz.
We managed to exceed this number by raising the North Bridge voltage by 0.4V and setting the FSB OverVoltage Control at +0.2V.
Together with the FSB overclocking of a quad-core processor, we confirmed that Gigabyte GA-X38-DQ6 can work with the memory clocked at very high speeds. With the FSB:Mem divider set at 3:4 we managed to speed up DDR2 SDRAM to 1267MHz with 5-5-5-15 timings.
Vmem was increased to 2.4V in this case. Moreover, we set the DDR Termination Voltage Control at +50mV.