We used the Core 2 Duo E8500 engineering sample (3.16 GHz at FSB1333 system speed) for the overclocking tests. Since we wanted the results to fit into the CPU Charts to allow for easy performance comparisons across various platforms and between both AMD and Intel, we worked with the components used when we first created these charts in the summer of 2007 instead of the new Reference Test System. While the CPU Charts system is still up to date (an X38 Gigabyte X38-DQ6 and a Foxconn GeForce 8800GTX), it also offers a nice setting to facilitate overclocking. The Gigabyte BIOS includes an auto overclocking setting, which automatically adjusts voltages once you increase the Front Side Bus speed. Note that the CPU Charts test system does not support DDR3 memory, but only DDR2-800 (which is not much of an issue from a performance standpoint). You really need high DDR3 memory speeds that DDR3-1600 offers to at least get a small benefit compared to DDR2-800. You will find the overclocking test setup below.
We used the Tom's Reference System to analyze and compare the power efficiency of the new 45 nm Core 2 Duo E8000 processor against three older generations of Intel processors.
The Reference System, however, which we use as the base line for many reviews and roundups these days, is based on DDR3 RAM. We used this system based on the Asus P5E Deluxe (X38 chipset) for the power consumption and efficiency analysis for Pentium 4, Pentium D, Core 2 Duo and Core 2 Quad processors. The RAM speed we selected was DDR3-800 for the FSB800 processor generation, as the 1:1 FSB-to-memory ratio is the fastest setting we could select, and DDR3-1066 for FSB1333 CPUs.
Core 2 Duo E8000 Overclocking
The overclocking approach for mainstream Intel processors is always the same; since you cannot increase the processor multiplier, you have to increase the second factor, which is the Front Side Bus. Every high-end motherboard based on Intel's P35 or X38 chipset will allow overclocking from the default 333 MHz (FSB1333 quad pumped) to at least 450 MHz. Well designed motherboards will extend the threshold beyond 500 MHz.