So I hear that the r9 270x and the 7870 are the same cards except the r9 270x is overclocked. I am working on my second build and I want to know if I am able to crossfire the r9 270x and the 7660D. I assumed I could crossfire the 7870 and the 7660D because they are the same series. Can those be Crossfired, or was I wrong on that too? (I only believe I can crossfire the 7870 and 7660D because I currently am crossfiring a 6530D APU and a 6670)