I have started building a pc recently, but due to limited budget i am buying a part after part. So far i have bought a motherboard and a PSU. My wish list is looking like this: Mobo: GA-P55-USB3 CPU:i5-750 GPU:1x HD Radeon 5850 RAM:2x2gb 1600 HDD:1x 7.200 rpm The PSU i have bought is Gigabyte Superb 550P which clams to have 450w continuous output and has 550w Peak combined wattage. Before buying psu i have spent some time on a calculator just to see that it shows a 352w minimum requirements, so i have decided that a ~450w psu would be enough. Althought after surfing net i have seen people going for 750watts+ with similiar systems built. This is my first time building pc, so im kinda lost here. Thanks in advance.