How To: Get A 4 GHz Dual-Core For $120

Why Core 2 Duo E7200?

Our overclocking processor of choice is the Core 2 Duo E7200. It’s based on the 45 nm Wolfdale core, but it runs at a lower bus speed than the E8000-series and it has half the L2 cache capacity: 3 MB instead of 6 MB. While there are still Core 2 Duo E4000 and E6000 processors on the market, the E7000 is effectively the entry-level Core 2 processor. Currently, there are only three E7000 models: the 2.8 GHz E7400, the 2.66 GHz E7300 and the 2.53 GHz E7200.

The same Core 2 Duo E7200 processor was part of our low-power systems comparison, in which we compared G31 motherboard solutions for office and multimedia applications. We found that these boards with the Core 2 Duo E7200 processors are capable of delivering mainstream performance at extremely attractive power requirements of just above 30 W.

E7200 Clocks Like E8500

We chose the E7200 because it runs on the same 9.5x multiplier as the Core 2 Duo E8500. The latter reaches 3.16 GHz on a FSB1333 bus and the 9.5x multiplier, while the Core 2 Duo E7200 reaches 2.53 GHz by multiplying 266 MHz (FSB1066) times 9.5. As a consequence, you can operate the E7200 at E8500 clock speeds simply by switching the bus from FSB1066 to FSB1333. Using the test motherboard’s automatic settings, we didn’t even have to increase the processor voltage manually to achieve 3.16 GHz with the E7200 processor.

Now we still have at least 20 percent additional headroom for overclocking when going from FSB1333 to FSB1600 speed (333 to 400 MHz base clock speed), which is another safe step considering that the same Intel architecture runs on FSB1600 speed at the high end. A further system bus increase to 500 MHz or higher enables more overclocking options for the enthusiast.

Cost Considerations

The Core 2 Duo E8500 lost our vote because of its stepping, which hasn’t reached M0 yet, and because of its substantially higher cost. While we found the Core 2 Duo E7200 on the Web for less than $120, the Core 2 Duo E8500 still costs $210 or more. Yes, the latter will provide better performance thanks to its 6 MB L2 cache, but the 75 percent cost increase by no means justifies the 5 to 10 percent maximum performance increase. See Does Cache Size Really Boost Performance for details. For this article, we analyzed performance with 4 MB, 2 MB and 1 MB L2 cache on systems running exactly the same clock speeds and hardware configurations.

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