I just purchased an Diamond HD 3870 512 MB card to replace my crossfired X1950 pro cards. I uninstalled the catalyst drivers and shut down the machine. I removed the old video cards, and installed the new card in the master PCI slot. Problem is, when I boot up the machine with the new card, the monitor does not get a signal. I am using a Viewsonic VG2030wm monitor, with DVI. I've tried both DVI ports on the card, and even tried switching the new card from the master PCI Express slot, to the Slave slot, with no luck. I have double checked that the card is properly seated, and that the 6 pin power cable is plugged in. I also checked to make sure that the master slot was working, by putting one X1950 Pro card back in. I am going to try driver cleaner, but I don't think this is the issue. I know that the new HD 3870 card is getting power and that the fan is running, but am baffled as to why it doesn't send a signal over the DVI to the monitor. Any input would be appreciated.