It's usually best to go for the single most powerful card you can, instead of using two for similar performance. Crossfire also isn't that effective, so isn't really the best option. XFX don't make very good GPUs, so I would go for a Sapphire 7950 instead. But the best advice I could give you is scrap both options and grab yourself an EVGA 760 for cheaper than the 7950, and just as powerful.