Your video card is absolutely bottle-necking your cpu, what that means is your cpu cant perform to its fullest extent because of the gpu holding it back. However, a 6670 should be able to run WoW especially with 8gb's of RAM. Download CoreTemp ( http://www.alcpu.com/CoreTemp/ ) and post your cpu and gpu temperatures. If overheating is the case, you might just need a thorough cleaning, if its serious overheating you might only need a new cooler ($10-$30). Let me know how it goes. Remember to choose best answer! -Cael
You could try lower settings, especially the shadows. You are also going to have issues with your CPU if you upgrade the GPU. WoW is pretty CPU hungry. It doesn't care about a lot of cores, only that they are fast.