MOBO support

So i have been thinking of buying a new CPU, FX 6300 or a FX 8320. I have an ASRock extreme 3 motherboard but im not sure if it supports 8 cores that well because i have read some stuff that the ASRock Pro3 MOBO just doesnt have that good preformance when having 8 core CPUs. So would i be better of just getting the FX 6300 and a cooler or the FX 8320?

Eh, FX-6350 and cooler. It should be sufficient.

well its depending on what you gonne do the FX6350 is also 125W tdp so thats the same storry as a FX8320/8350

The problem with those asrock boards, i name 970A extreme 3 and 4 and also the 990FX extreme 3, have only a 4+1 powerphase, and weaker vrm´s. the best way to go is putting a FX6300 95Wtdp cpu onto it, if you wanne stay long at this mobo.

you can ofc also run a FX8320 on it, if you update the bios to the latest version, but the problem is, with those weak vrm´s and only 4+1 powerphase you won´t be able do to any overclocking. those boards are just to weak for that. and the board will probably life less longer.but yeah if you stay at stock speeds, and plan to upgrade your mobo to a decent 990FX chipset board from asus or the Asrock extreme 9. then you could go with a FX8320/8350 now. but if you wanne stay long with your  extreme 3 board, then pickup FX6300

i thought that i just need the new catalyst version and not the bios

catalyst has totaly nothing to do with it. you need a bios update.