If you really want an upgrade why not get one of the new R9's and crossfire it with your 7950. The 280x is equivalent to a 7970 ghz edition and compatible to crossfire with 7 series cards. While your 7950 is slightly slower, even with the R9 dropping down to the speed of your 7950 you'll still get a nice performance boost in games that support crossfire, and can run the R9 alone for games that dont.