Why Are You Upgrading: I do a lot of gaming, League of Legends, Assassins Creed III, Bioshock series, just about any steam game, my ps3 broke so I switched to PC gaming but the rig I have I built as a budget that would play League not really expecting to get into PC gaming. What I have will handle most of my games but at barely 30fps and on medium to low quality and I would like to be able to get closer to the 60fps range with higher settings. I just don't want to spend more than what I need to to get decent gaming performance since it's the only thing I really use it for aside from watching videos. Thank you in advance for any advice.
Good build. The 7870 you choose runs off the Taihiti GPU so it's an awesome card to say the least.
Maybe consider another MB. Not real sure of Biostar's track record with Motherboards or the quality of them.
Newegg has other motherboards that have RAM bundled with them. Maybe consider a AsRock, ASUS, Gigabyte, or a MSI board. They are all good quality manufacturers.