Hi, I'm just confused in choosing a PSU for my build. I don't know what PSU should I buy because I don't know how much total power(wattage) will be used by my build
I am really a newbie 
Here are the parts that I've picked
CPU: Intel Core i5 3570k
Motherboard: AsRock Z77 Extreme 4
GPU Card: Probably an AMD R9 280x or AMD HD 7970 OC Edition
Case: CM Storm Scout II Black ( Already Purchased )
Memory: Crucial Ballistix Tactical Tracer 1866mhz 8gb Dual Channel Memory Kit
Storage: Western Digital Caviar Blue 1TB 7200 RPM
Accessories: 5x 120mm Case Fans
I will be slightly overclocking my system.
Q: How much total power(wattage) will my build use ?
Q: What PSU will you recommend ?
Lately, I wandered on some reviews and found a PSU Wattage Calculator, which recommended a PSU with a wattage of 549 W.
Q: If my build only uses a wattage of 540-600 W does a PSU with 600 W is enough ? or Must I consider a PSU with a wattage of 10-20% higher than the calculated total wattage of my system ?
Q: Which PSU is better the Corsair CX600M or the Antec HCG620M if a 600 W PSU is enough?
I will be considering buying the Corsair TX750m if my build uses a wattage of 600+


Here are the parts that I've picked
CPU: Intel Core i5 3570k
Motherboard: AsRock Z77 Extreme 4
GPU Card: Probably an AMD R9 280x or AMD HD 7970 OC Edition
Case: CM Storm Scout II Black ( Already Purchased )
Memory: Crucial Ballistix Tactical Tracer 1866mhz 8gb Dual Channel Memory Kit
Storage: Western Digital Caviar Blue 1TB 7200 RPM
Accessories: 5x 120mm Case Fans
I will be slightly overclocking my system.
Q: How much total power(wattage) will my build use ?
Q: What PSU will you recommend ?
Lately, I wandered on some reviews and found a PSU Wattage Calculator, which recommended a PSU with a wattage of 549 W.
Q: If my build only uses a wattage of 540-600 W does a PSU with 600 W is enough ? or Must I consider a PSU with a wattage of 10-20% higher than the calculated total wattage of my system ?
Q: Which PSU is better the Corsair CX600M or the Antec HCG620M if a 600 W PSU is enough?
I will be considering buying the Corsair TX750m if my build uses a wattage of 600+