For the C-Ray multi-threaded ray-tracer, PC-BSD 9.1 and CentOS 6.4 were the slowest. Within GCC and LLVM/Clang there's been some performance improvements in recent versions that have enhanced the C-Ray performance, which likely explains the slowdowns. Mageia 3 was still running slower than the rest from this Core i7 3960X. Worth pointing out as a possible explanation for some of the performance differences is the Mageia 3 is using the performance CPUfreq governor on this six-core + HT system where as the other Linux distributions were using the ondemand governor.
When it comes to the Primesieve prime number generator, the numbers weren't too interesting except for PC-BSD 9.1 and Mageia 3 being the slowest.
There isn't too much new information to share from N-Queens.
Mageia 3 was the slowest operating system for the Rodinia scientific benchmark.