Games run terribly choppy and my framrate doesn't stay at a consistent number!

[brantnergrace]

I have recently installed a new power supply and it is a really good EVGA one 700w I installed it because my other one was damaged. Now whenever I try and play a simple game like CS:GO it is really choppy and the framerate isn't consistent. It can be 60fps for like 5 seconds and then drop to 10fps. Any help would be appreciated.
Specs -
Motherboard - msi z97 gaming 5
CPU - Intel i7-4790K
RAM - 16GB
GPU - GeForce GTX 750 TI

 

[Slovenia rulez]

Did you plugin the extra 8pin cable for the motherboard or your cpu may not get enough power?