PC Building help

I'm building my first PC to play some games and just want to know if the components listed below are all compatible. Also need help on finding RAM and not too sure on the video card, thinking about going with the SAPPHIRE R9 270x 2GB GDDR5 Dual fan but not sure if its compatible or I could get another one thats better. Thanks guys.



H87 LPUS ASUS Motherboard



Intel i5 processor



CS Series Modular CS550M — 550 Watt 80 PLUS Gold Certified PSU (not too sure on wattage, help?!)



Corsair Graphite series 230T Windowed Compact mid tower case