I just looked on Amazon ES and there's a 'Dual-X' (what does that mean, by the way?) Sapphire 2GB VRAM GPU R9 270x for around 175€, while the HD 7870 GHz Edition is 205€. How is that? Some people say that 270x is better. And what's the difference between SAPPHIRE TOXIC and SAPPHIRE DUAL-X 270x?