I am a WoW player and will sometimes jump into Dragon Age. I also played the SWBF Alpha which ran just fine. My system is an 8 core AMD CPU with a Radeon HD 7900 on an Asus ROG motherboard.
This sounds really close to my rig's hardware (and typical software).
I was running Windows 7 before and attempted to do an in-place upgrade initially but it failed despite trying many different things. I ended up installing clean from an ISO and have been on the fast ring ever since.
My installed OS is 8.0 home (recently upgraded to 8.1 from the app store), and the exact same thing happened to me. In-place upgrade fails no matter what I try. So I used their tool to create an ISO. However, it asks for a license key and won't take my Win 8.0 key. How did you get past that?