From overclockers’ standpoint Asus P5E mainboard features a very good BIOS Setup. Let’s see how Asus P5E will behave in practical overclocking experiments. Our overclocking testbed included not only this actual board, but also 2GB DDR2 from Corsair (Dominator TWIN2X2048-8888C4DF), OCZ GeForce 8800GTX graphics card, Western Digital Raptor WD1500AHFD HDD and SilverStone SST-ST85ZF power supply unit. We used a Zalman CNPS9700 LED processor cooler, too.
First of all we decided to determine the maximum FSB frequency when the board would remain stable and reliable. We tested with a Core 2 Duo E6750 processor. For stability check we ran Prime95 25.3 program for 30 minutes in Large FFT and Blend modes.
Asus P5E proved totally up to our expectations. Our processor was running stably without any problems at up to 440MHz FSB frequency. We didn’t even have to change any voltages other than Vcore and Vmem for that. However, further overclocking led to evident instability, so we had to dig a little deeper into system fine tuning.
Further tests showed that FSB frequency increase above 440MHz requires raising the North Bridge voltage. By raising this parameter only to 1.4V we could push the FSB speed to 465MHz. with the North Bridge voltage at 1.55V the board runs flawlessly at about 500MHz FSB, although in this case an additional fan is required on the chipset cooling system.
The maximum overclocking result was achieved at 1.65V North Bridge voltage. In this case the board would start and remain stable at 520MHz FSB.
We didn’t have to increase CPU PLL Voltage and FSB Termination Voltage, they were at their default values of 1.5V and 1.2V respectively. The memory was clocked using 1:1 divider at 1040MHz with 4-4-4-12 timings.
I have to stress that further increase of the North Bridge voltage didn’t have any positive effect. The FSB overclocking potential would drop that indicated chipset overheating and required replacing the chipset cooling system with something more efficient.
However, contemporary mainboards have been coping successfully with dual-core processors overclocking for quite a while now. It is the quad-core solutions that seem to be of most interest these days. Therefore, the second part of our overclocking experiments was devoted to Core 2 Extreme QX6850 overclocking.
I would like to say right away that quad-core processors overclocking on Asus P5E mainboard is as simple and quick as dual-core processors overclocking. To achieve maximum results it is enough to simply raise the processor Vcore, Vmem and chipset North Bridge voltage following almost the same rules as in the previous case.
However, maximum FSB frequency when the board remained stable turned out considerably lower than in the previous case. Our best result is 460MHz.
We increased the chipset North Bridge voltage to 1.55V; CPU PLL Voltage, FSB Termination Voltage and CPU GTL Reference were at their nominal values. The memory was working at 1105MHz with 4-4-4-12 timings, i.e. we used 5:6 FSB:Mem divider.
By the way, the North Bridge temperature hits 70-75ºC during such quad-core processor overclocking, despite the additional fan included with the mainboard. It is another indication that Intel X38 platforms are more dependent on efficient chipset system cooling than Intel P35 based ones, because the new North Bridge dissipates almost twice as much heat.