Even a bad PSU can cause poor component performance. And it will definitely bring stability issues. Change the PSU to something like a Corsair TX 650 V2. It has more than enough to support your current rig and will keep you powered for more powerful upgrades you make in future.
Your CPU will not cause any significant bottlenecks. You can reduce the drag by upgrading to a bigger monitor wherein the higher resolution will cause lesser strain on the CPU and more on the video card.