POWERTOWERPRO  The artifact issue with the GPU is a known rev1 problem and if you mac is still under its one year warranty a quick call to apple care will get you a brand new rev 2 card. I did this 2 months ago. There is a HUGE forum on blizzard on this. Tons of people have got new cards. Here is the link (you can thank me later):

http://forums.worldofwarcraft.com/thread.html?topicId=94000596&sid=1

My post with direction on how to handle the apple care reps:

http://forums.worldofwarcraft.com/thread.html?topicId=94000596&sid=1&pageNo=10

Read the post from "Elderclass" Thats me.  
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