CPU: Intel Core i5-2500K 3.3GHz Quad-Core Processor Motherboard: ASRock Z68 Extreme3 Gen3 ATX LGA1155 Motherboard Memory: G.Skill Ripjaws Series 8GB (2 x 4GB) DDR3-1333 Memory Storage: Seagate Barracuda 500GB 3.5" 7200RPM Internal Hard Drive Video Card: Sapphire 11199-00-20G HD7870 2GB GDDR5 Graphics Card Case: Cooler Master CM Storm Enforcer Power Supply: OCZ 550W ATX12V Power Supply Optical Drive: Sony DDU1681S-0B DVD/CD Drive Operating System: Microsoft Windows 7 Home Premium SP1 (64-bit) CPU Cooler: 212 Hyper evo This is the build i will get betting soon. I may or may overclock the 2500k to around 4ghz in the future.
Is my current PSU Good enough if i do overclock? (Also do OCZ make good psu's?) IF i overclock my gpu, will i need even more PSU Wattage?
More aboutquestions wattage
OCZ makes solid to very good PSU depending on the model. OCZ has several 550w PSU including the ZS, ZT , and fatality to name a few but you don't state your exact PSU. All can power your system even with an OC.
OCZ are one of the 'trusted' PSU companies, you should be fine with one of theirs.
To anwswer your overclock question - yes, more power is used if you OC your CPU/GPU, but as ct1615 has said, your 550watt will be sufficient.