How do you compare single and dual cores power

Core clock rating these days is pretty much useless other than to compare a processor in the same line to another in the line. The reason is that there are a lot more factors than core clock rate. For example one core in a 2.0Ghz core duo is faster than a 3.2Ghz P4. There are many reasons for this which in include faster FSBs in the core duos allowing faster memory access which keeps the processor busy without stalling much. There is also much better branch prediction in the core duos and various other architecture improvements which allow better performance under lower clock speeds.

Unfortunately the move to dual core has made clock rating suggestions impossible. This 2.0 dual core = 2.8 single core is really just a huge amount of BS made up in attempts to resolve the issue at hand and really depends on the program itself. A well designed program can get nearly double the performance out of a dual core system than a single core system but a badly designed program might only see a 1% increase using two cores. And yes applications have to written to take advantage of dual cores. If they aren't then your application is running at 2.0ghz on one core, BUT other applications can run on the other core so there is still an advantage to a dual core system even if every application running is designed only for a single core.

The only rule of thumb I can provide right now is that the lowest clocked dual core is for the most part faster than the highest clocked single cores even when running on a single CPU meaning any dual core is going to be able to handle the requirements listed for a single core CPU. And a year from now I imaging single core clock speeds simply won't be listed on software. And again, there really isn't a general rule to be able to convert the clock speed of a single core to the overall clock speed of a dual core because that is completely dependent on the program itself and how it utilizes each core. Thats why most programs list single core requirements then dual core requirements separately.

Jam it back in, in the dark.