GPU or CPU?

[Alexguy891]

I have
AMD FX-6300 3.5GHZ
8GB DDR3
GTX 960 2GB
500w PSU

I was wondering if I should upgrade my 960 to a 1070 like I was planning and have a CPU bottleneck or upgrade my FX-6300 to an i5-6600k? Also if I did what else would I need besides a new motherboard and possibly new RAM.

Edit: This is for gaming for First Person Shooter games like Battlefield.

 

[clutchc]

it will depend on what you want the upgrade for. If gaming on a busy server, the CPU is the first needed upgrade. If gaming at single player, you can go a bit higher in performance before CPU bottleneck gets too bad.