Rising fury said:
PC specs :CPU Intel core i5 4670 LGA1150 GPU : Nvidia GeForce GTX 660, MOTHERBOARD : Asus Z87-A, Power supply: Antec HCG-750 (750VW) RAM: Corsair Vengance 2x4gb CASE: Raidmax ORION
your specs are ok and that psu is a good one and more than enough for your system. even so, make sure power supply fan is spinning and not overheating. also make sure you have replugged the cpu fan header as suggested earlier!
you can even try re installing the gpu. if all fail, remove everything except cpu and one stick of ram and see if you will have a post. if you do, re install all parts one by one to find the possible fault one