If u already do not have the A8, best option for best performance would be the 6300, and the A10 has the same cpu power as the 965 x4 as seen in the comparison charts, and getting the A10 would be just because its newer, but the x4 is slightly better and usually is around $90 and a am3+ board gives option for upgrade to steamroller later this year
if u have the A8 well the just test the gameplay with the 670 and go from there. as i said the quad core on the apu is not bad as most games barely use 4 cores, but crysis will stress it, something like guild wars may not, and really it was just the 3.0ghz lol i did the same to my 2.8ghz x6, 400mhz bump and im prob sure there is barely a difference that id notice lol