Various Dual CPU Results

Chart of a 2 CPU Alpha EV68 with 1 GHz running Tru64
Chart of a 2 CPU Alpha EV68 with 1 GHz running Tru64

Chart of a 2 CPU Itanium II with 1.6 GHz running Linux
Chart of a 2 CPU Itanium II with 1.6 GHz running Linux

Chart of a 2 CPU PA-RISC 8900 with 0.8 GHz running HP-UX
Chart of a 2 CPU PA-RISC 8900 with 0.8 GHz running HP-UX

Chart of a 2 CPU Pentium III with 1 GHz running Linux
Chart of a 2 CPU Pentium III with 1 GHz running Linux

Chart of a 2 CPU Power III with 0.45 GHz running AIX
Chart of a 2 CPU Power III with 0.45 GHz running AIX

Chart of a 2 CPU Xeon with 3 GHz running Linux
Chart of a 2 CPU Xeon with 3 GHz running Linux

Conclusion
As you can see, the results are almost linearly dependend on the core frequency of the CPUs.
The most interesting result is from the Power III sysytem running AIX, it is the only sysytem where the time increases significantly when using more than 2 threads but decreases again at about 22 threads. But again, the maximum time is approx. twice as big as the minmum time.