er..whats the different between 790 and 780G chipset?
I think the major difference is the integrated video, the 790 has a better built in video card but that shouldn't matter if you're buying a dedicated video card. The 790 might allow for more stable overclocks as its a highend chipset. I'd buy the cheapest of the two if it means that you can get a better CPU, for example you'd be better off getting a cheaper 780 or a cheap Nforce 8300 if it means that you can put the extra money towards a Phenom II X4 810 or 940 instead if you catch my drift.
Edit:
i see.. then is 780G chipset doesn't have ACC feature? exp:M4A78 PRO <-- does this mobo has ACC feature?
I'm not sure. What is the price difference between the X3 720 BE and X4 810? if its a small price gap just get a "cheaper" motherboard without ACC and put the money towards an X4.
If you want to unlock cores the Phenom II X2 550 can unlock too, its cheaper than the 720 BE and the majority of the time the cores are not faulty.