I am planning to make a pc but i am wondering if i should use FX 6300 or A 10. Fx 6300 has normal clock of 3.5 GHz and 4.1 when turbo boosted but A 10 only has 3.4 GHz.but i wonder what cpu i need to run Company of Heroes, Simcity 5 and GTA 5.
That really depends on wether or not your budget allows for a processor and a dedicated graphics card. The A10 has a decent card built in, so if you can't afford a dedicated card its the way to go. The FX 6300 is a faster processor, but with no built in GPU only make sense with a separate card.
The difference in processing power will not be felt for those applications. For those games the A10 will run on high detail, but some additional features off. With the 6300 , you have to purchase an additional GPU. My best bet,purchase the A10 and run the games, if you want better, you can purchase the same GPU you had to buy with the 6300 (probably a better one since you have a few dollars more) and problem solved.