Just to add my voice (as an R9600PRO user, an the resident 'know-it-all' for R9600s);
The major difference is in the quality of the memory and the potential of the cores. They ae the same cores on paper, but likely the lesser cores get off-loaded onto R9600non-pros (based on the poor overclocking results I've seen). The memeory on R9600N-Ps is TSOP, whereas the memory on R9600PROs is BGA. BGA is a better method of connections and the memory used is usually of better quality (both leading to better speeds especially in overclclocking).
It all comes down to speed. Thee are no pipeline or architecture diff. between the two, however the core and memory speeds start off diff. (usually 325/200[400] vs 400/300[600]) the 'chip's themselves are basically the same, except as I mentioned the core's potential speed.
And I'd say go with the PRO if you can afford it. It's the better choice IMO. Which is why I have one.
<A HREF="http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=353530#353530" target="_new">HERE</A>' my original thread on my experiences (up to a point; it's an old thread).
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