Unfortunately, we do not see the same close results in the overclocked mode because all mainboards overclocked the processor differently. The following table sums up our overclocking results:
A 100 MHZ difference in resulting processor frequency produces about 2% performance difference. So, 4.2-4.5% performance difference between Asus Rampage IV Formula, which overclocked the CPU to its maximum of 4.7 GHz, and MSI X79A-GD65 (8D), which only reached 4.5 GHz, is quite normal.
It is very easy to compare the results of the MSI X79A-GD65 (8D) mainboard against the other products that also overclocked the processor only to 4.5 GHz. As you can see, these systems are almost equally fast, even though a lot depends on the test application and on the unique features of the given mainboards. For example, in Adobe Photoshop CS5 and 7-zip 9.20 both Micro-Star mainboards are noticeably slower than the others, and both ASRock boards yield to the competitors in Resident Evil 5 game.