amd gpu cpu hp upgrade athlon

I have AMD Athlon 6000+,an old HP 0a64h mobo, 4 gb ram, latest windows 10, and a burned AMD HD 6670 1GDDR5... I thinked to buy an AMD HD 7770 or 7790 for playing medium games. While playing, nothing is working in the backround, i use Razer Cortex + cpu overclock. Would the cpu bottleneck the...