CPU: Intel Core i5-4690K
MOBO: MSI ATX Z97 GAMING 5
GPU: EVGA GeForce GTX 960 4GB
Power: FirePower Technology ZT Series 550W
CPU Cooler: Thermaltake Technoloy NiC C5 120mm Untouchable
Case: Enermax Ostrog GT ATX Mid Tower
RAM: Corsair Vengeance 16GB (2 x 8 GB) DDR3 1600 MHz
1) Get rid of that GTX 960 4GB, not worth it consider that 128 memory bus will slow you down. Get GTX 970 4GB that will be future proof 1080P gaming.
2) Get rid of that power supply, not highly recommend as it can kill your entire computer. I recommend these Seasonic or Antec. If in the future you want to build a computer with a good power supply, highly recommend EVGA, Seasonic, and Antec as they produces good power supplies.
3) Drop that CPU cooler and get this instead. Coolermaster Hyper 212 EVO
4) I will give you a list of good and bad power supply lists, so later on you can refer to it. Highly recommend bookmark these.
Good power supplies lists
Bad power supplies lists