You need to have two of the same GPU to do crossfire/SLI I have seen the same GPU but two different brands work together, it's just they definitely have to be the same card and have the same memory. I think what your asking is if you can use the same gpu just one is Radeon and one is Sapphire? If so, it should work if there the same memory and chipset, but whichever one has the lower clock speed is what the other GPU will sink to. I think its easier to just get two of the exact same card.