[citation][nom]akula2[/nom]I don't quite agree with this review on Gigabyte P55A-UD6. Most of the other top review sites clearly placed UD6 ahead of the Asus, how come it's different in this review?[/citation]
You mean ahead of Asus in Performance? Tom's sets the BCLK to 133 MHz, some other sites use "Auto": If Gigabyte overclocks to 136.3 MHz at "auto" and Asus doesn't, that makes it appear like Gigabyte performs better even if it doesn't. Tom's doesn't play those games, taking great effort to eliminate "Cheating".
Look at the performance comments in the conclusion. Tom's specifically cancels-out Asus' 0.28% overclock at the 133 MHz setting in those comments. Gigabyte's 2.7% "default overclock", if allowed, would have been nearly TEN TIMES as bad. Rather than heap on ten times the criticism for cheating, Tom's takes the "high road" by setting 133 MHz manually.
So to get straight to your question, the reason Tom's numbers are different is because, by doing what it can to prevent cheating, Tom's produces a higher degree of accuracy. This is reflected in the article quote "Since our performance charts reflect base clock massaging more than real-performance differences, we can’t quite base our final analysis on these."
If you don't like accuracy, feel free to disaggree!