ASUS P5B provides some basic overclocking options. On ASUS P5B (0904 BIOS) you will find the following overclocking options:

• FSB clock: Can be adjusted from 100 to 650 MHz in 1 MHz steps.
• PCI Express clock: Can be adjusted from 90 MHz to 150 MHz in 1 MHz steps.
• CPU voltage: auto or from 1.2250 V to 1.7000 V in 0.0125 V increments.
• Memory voltage: auto or 1.8 V to 2.1 V in 0.1 V increments.
• FSB termination voltage: auto, 1.2 V or 1.3 V.

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Figure 5: Overclocking options on P5B (0904 BIOS).

This motherboard also provides memory timings adjustments, feature not found on other P965-based motherboards we reviewed. This option, however, is hidden under Advanced, Chipset, North Bridge Configuration menu, and you need to change the “Configure DRAM Timing by SPD” option to “Disable” for the memory configurations to show up. Also, depending on the BIOS version your motherboard is using, you will find more or less options here. Our board came with 0211 BIOS, which provided only the four basic timings adjustment, but after we upgraded the BIOS to version 0904 all the options shown on Figure 6 appeared.

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Figure 6: Memory timings adjustments on P5B (0904 BIOS).

The PCI Express clock configuration is very important, as you can lock the PCI Express clock at a given value (100 MHz, for example). Usually when you increase the FSB clock you will automatically increase the PCI Express clock as well, and sometimes your overclocking will be limited not by the CPU but by the devices connected to the PCI Express bus. Thus with this option you can increase the probability of setting a higher overclocking.

We could only find one feature missing: a separated clock configuration for the x16 PCI Express slot. But we think that the features present will satisfy almost all users. Of course if you want even more overclocking options, you will need to buy a high-end motherboard. It is important to say that Gigabyte GA-965P-DS3 and MSI P965 Platinum have more overclocking options – but they don’t have memory timings adjustments.

With this motherboard we could increase the FSB clock of our Core 2 Duo E6700 from 266 MHz to 316 MHz and the system worked just fine. We locked the PCI Express bus at 100 MHz and configured the memory as DDR2-800 in order to keep them under their specs.

The overclocking we achieved represents an 18.80% increase on the CPU internal clock, making our 2.66 GHz Core 2 Duo E6700 to run at 3.16 GHz. The performance measured by PCMark05 increased 11.76% and the performance measured by Quake 4 increased 18.18% with this overclocking. Really nice.

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Figure 6: Our 2.66 GHz Core 2 Duo E6700 running at 3.16 GHz (316 MHz x 10) on ASUS P5B.

This was a better overclocking than the one we achieved with MSI P965 Platinum (306 MHz) and with Gigabyte GA-965P-DS3 (308 MHz).

It is very important to keep in mind that our overclocking is limited by the overclocking capability of the CPU we used, a Core 2 Duo E6700. Also, the CPU overclocking capability is not only defined by the CPU model, but also by its production batch. You may achieve better results with different CPUs and even with the same CPU model but from a different batch.

We didn’t play with voltage adjustments or any other fancy adjustments, so you may achieve a better overclocking than we did with more time and patience.