Overclocking an unfamiliar processor to its limit usually requires increasing clock speed and voltage separately, in small increments, until additional voltage provides no increase in clock speed. But that unfamiliarity can lead to settings that significantly shorten the component’s lifespan. On the other hand, the old fashioned “safety” rule to increase voltage by no more than 10% would have left these products far short of their true potential.
Today we used four processors that have been on the market long enough to determine vital information such as the maximum tolerable voltage and life expectancy. Using slightly less than the “maximum long-term safe” voltage allowed an almost-stunning 64% clock speed gain on Intel’s Pentium E5200. Plus, if this architecture's history is a good indicator, there's a strong likelihood that the part will survive many months to several years of use. As stated in several System Builder Marathon articles, we specifically recommend this $70 processor for ultimate-value overclocking.
The biggest let-down was the Core 2 Quad Q8200, a part that actually contains two of the same dice as the E5200 under its lid. The problem of a “locked” multiplier becomes critical on an FSB-1333 CPU that can’t reach FSB-1600, and Intel doesn’t offer a cheaper, FSB-800 version to play with. If you wanted a more rewarding experience with this chip, you'd likely need to spend extra on the low-power 'S' version.
Anyone who really wants the best overclocking value from a quad-core could easily look to the Phenom II X4 955 Black Edition or Core i7 920 as safe bets. The Black Edition’s unlocked multiplier guarantees a lack of drama over HT clock, while the i7-920’s well-known tolerance to increased base clock speed makes unlocked multipliers an afterthought. But while our X4 955 Black Edition proved its capabilities at 3.86 GHz, the price of entry for the competing Core i7-920 was just a little beyond the budget of today’s guide. Disappointing headroom in the Q8000-series and a price-exclusion for Core i7 allow AMD's Phenom II X4 955 Black Edition to earn our value-overclocking recommendation for quad-core CPUs.