I am buying a gaming pc but want to make sure i am getting the best for my price i have 30 dollars left in what could i spend that http://pcpartpicker.com/p/mWNTjX
Would changing the CPU to a FX- 8350 make a big difference in my game play with that money i could buy a GTX 970 would this be better?
No stick with the i5, but going to the non k 4590 is a good idea. (as you arent using a Z87/Z97 board).
I want to be able to overclock thankyou
Then you will need to spend more and preferably get a Z97 board, but it will make it less good in games if you have to pick a lower GPU - overclocking wont help you much (stock clocked hw/dc i5 is fast enough).
If you want to overclock, you need a Z97 or older Z87 board, the stock cooler will need to be upgraded significantly and with a high-power use Radeon GPU, you may need to add or upgrade case fans for improved thermal control.
Your Corsair CX PSU is tier 3 and something better would be advised for overclocking. You also need to check on TDP for the system at peak and make sure that your PSU is good for it.