Something like that.
The first two cores are used in the same manner as the current version (9.6 and r1888), 1 for the emulator and one for the GS.
The third one is used for the GUI.
So it won't be like "ZOMG 500FPS!!11!one", but at least it's a little bit faster (especially on slower triples and quads).
Nappa: Vegeta! What does the scouter say about his power level?
Vegeta: It's...one thousand and six.
Vegeta: Yeah! Beat him up Nappa!
Yeah and people keep mixing up cores with threads. It's 3 threads, so for example a Core i5 that has 2 cores and 4 threads will take benefit from 3 threads of PCSX2. Anyway as dr_thrax already mentioned, it's hardly a speed increase but does help in program responsiveness.
To gain a benefit from 3rd CORE you should made 3 threads with balanced load. So you task should be able to divide in 3 parts, and each part should have noticeable load. Right now pcsx2 load is divided by 70/30 (EE/GS), so minor threads, that could be obtained from GUI or something else, would be easily executed on 2nd CPU.
So only way to gain a benefit from 3rd core is to divide EE thread into two noticeable parts, and that's almost impossible.
It will. Your OS does not see 'cores' but only threads. So if you have a dual core system (without hyperthreading) the OS sees 2 threads. If you have a quad core system , the OS sees 4 threads, if you have a dual core system with hyperthreading the OS sees 4 threads (2 actual cores and 2 virtual from hyperthreading).
Thanks for your help. In this case I'll try to unlock one more core from my cpu to try if there will be any difference between 2 and 3 cores. Phenom II cpus don't have hyperthreading I believe so the only option will be 3 real cores.
AMD Phenom II 550 Black Edition @3.8GHz
4GB DDR2 1066MHz CL5-5-5-15
ASUS Radeon EAH4770 Formula 512MB DDR5