Right now I'm running a HIS HD 4870 512mb video card, which has unfortunately gone bad on me and will need to be returned to the manufacture. I've been wanting to have a crossfire set up for a while now but until now I've never had the motivation to blow money on a new card. I know when doing a crossfire on two cards it's a good idea to have two cards with the same memory size as well as having the same GPU and Memory clocks. I can't find the same HIS 4870 I bought back in October so I'm looking at getting a http://www.newegg.com/Product/Product.aspx?Item=N82E168... ...the problem is the memclock on my old 4870 is 900MHz and memclock the XFX card is 3600MHz. My understanding is that when you crossfire two cards with different clock speeds it takes the fastest card and slows it down to the slowest cards speed. In this case it would under clock the XFX's memclock to a 1/4 of what it should be! Does anyone know if this would cause any problems for the XFX card? If not do you think that it would be a good idea to CrossFire these two cards or should I find another card to CrossFire with my HIS?