I just put in a 1GB HD4870 next to my older 512MB HD4870. CCC now says that the cards are "not perfectly matched" and says performance may not be optimum. I'm guessing that the message pops up because the cards have different memory sizes? If so, does that mean that only 1GB (2x512MB) will be used instead of the available 1.5GB? Is performance in any other way compromised, e.g. the second GPU is not fully utilized? Both cards have the same clock frequencies. I do see a (positive) performance difference in some games, so I guess it's not as bad as the CCC message suggests? Thanks in advance for your answers!