Is this build good for gaming and will I be able to overclock it?

Hi, I have basic knowledge of PC's, but I'm no expert. I need some reassurance whether or not this build is good. I would greatly appreciate if you would comment what I should change, or if it's ok.
Case: Corsair Carbide 300R Midi Tower Sort
PSU: Cooler Master Silent Pro M2 620W PSU
CPU: Intel® Core i5-3570K Processor
Motherboard: MSI Z77A-G43, Socket-1155
DDR3: Kingston DDR3 HyperX 1600MHz 8GB
GPU: XFX Radeon HD 7970 3GB GDDR5
DVD/CD: Samsung DVD Writer, SH-224BB
SSD: Samsung SSD 840 Series 120GB 2.5" BULK
HDD: Seagate Barracuda® 2TB
Wireless Network Adapter: ASUS PCE-N15 11n PCI-E Adapter
Thanks in advance.