Knowing that a Pentium Dual Core should be capable of reaching the processor speeds of its Core 2 Duo brothers, which currently max out at 3.0 GHz, it's important to find a suitable motherboard that can get our 1.8 GHz part up to this speed level. We selected a Pentium Dual Core E2160, which has been specified to run at a core clock speed of 1.8 GHz. The 200 MHz system bus speed represents effective performance of 800 MHz, because the protocol is based on quad data rate transmission, allowing four data transfers per clock cycle. However, the physical clock speed remains at 200 MHz, and the speed is referred to as FSB800.
This processor utilizes a multiplier of 9 to achieve its 1800 MHz core clock speed, based on a system speed of 200 MHz. Most Intel processors available today can also be operated at lower multipliers, because the SpeedStep feature - which is responsible for saving energy by reducing clock speed and core voltage when the system runs idle - has to be able to do its job. Accordingly, processors support several other, smaller, multipliers of 8x, 7x and 6x, which SpeedStep uses to run 1600 MHz (x8), 1400 MHz (x7) and finally 1200 MHz (x6), the last of these representing the slowest available speed. At the same time, processor voltage is adjusted to enable further energy savings.
Knowing about the multipliers, it becomes obvious that such a processor can only be overclocked by increasing the other multiplier, which is the system clock speed. The only exceptions are the Extreme Edition processors, which come totally unlocked to allow users flexible overclocking. Front Side Bus overclocking isn't a challenge anymore these days, because today's mainstream CPUs run at FSB1066 and FSB1333 speeds. If you select a motherboard that is based on the Intel P35 or G33 chipsets, or one of Nvidia's nForce 6 models, it should be capable of supporting FSB1333 right away. This represents a 66% clock speed increase over FSB800, and even FSB1066 is still a 33% increase. However, we mentioned an overclocking potential of up to 80%, which of course requires a larger overclocking margin on the motherboard side.
If you purchase a new Socket 775 mainstream or high-end motherboard that is based on a current chipset, you should be able to hit 400 MHz right away, probably even more. High-end motherboards with sophisticated component cooling solutions, paired with overclocking memory (typically you'll overclock your RAM as well) often even exceed 500 MHz base clock speed, which equals FSB2000. Note that the only systems that legally run at 400 MHz base clock today are the new Intel Xeon servers based on the Harpertown quad core and FSB1600 speed.
You have to pay attention to the motherboard, because what you want is a model that allows you to alter the system speed manually, modifying the memory speed settings and at least the CPU and memory voltage. While the FSB speed shouldn't be a problem in our scenario, where we increase the FSB800 stock speed to FSB1333 and above, memory speed is an issue. As soon as you exceed DDR2-800 speed, you might have to increase the memory voltage or even use overclocking memory designed for high clock speeds. However, let's not forget that we're dealing with a $89 processor, which is why we don't want to fuss with expensive cooling or enthusiast memory.
Some Socket 775 motherboards for Core 2 Duo and similar processors start at $60, but you can also spend as much as $300 for a high-end gaming motherboard. How much do you have to spend to get a decent board? For the Pentium Dual Core E2160, the entry point is rather affordable, as you will only need a basic motherboard with support for FSB1333 and simple overclocking options. Setting the E2160 to FSB1333 speed (333 MHz) will result in a core clock speed of 3.0 GHz. It may require slightly increased voltage, but you don't have to overclock other components.