Remove the Powercolour HD 6950 at this stage and only Select the Sapphire HD 6950 and install it in PCIEx16 [top slot] and attach power cables
power up and boot into windows
go here - Control Panel\All Control Panel Items\Windows Update\Change settings and set Important updates to *Download updates but let me choose whether to install them [Note: this can be changed back afterwards]
go here - http://www.softpedia.com/progDownloa...oad-18442.html
and download this app [*may be required]
go here - http://support.amd.com/us/gpudownloa...w_vista64.aspx
and download catalyst 12.10 [or a version of the catalyst drivers you know work]
Manual Uninstalation Of AMD Drivers in Windows 8
*be careful not to remove AMD chipset drivers and or reinstall them if required*
1. Run the Application Profiles (CAP) uninstaller from 'Programs and Features', select 'No' to restarting now.
2. Run the AMD uninstaller from 'Programs and Features'. Express uninstall all ATI, select 'No' to restarting now.
3. Uninstall any leftovers in the case that step (2) fails ; use Windows Installer CleanUp Utility 126.96.36.199
4. Manually delete all AMD and ATI registry entries from HKEY_CURRENT_USER\Software, HKEY_LOCAL_MACHINE\SOFTWARE, and HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node
5. Manually delete any AMD or ATI folders from C:\Users\<YourUserName>\AppData\Local, C:\Users\<YourUserName>\AppData\Roaming, C:\ProgramData, C:\Program Files, and C:\Program Files (x86)
6. Manually delete any AMD and ATI related files from C:\windows\system32 and C:\windows\syswow64 -- for this step use the command prompt:
7. Under Device Manager, right click your AMD card(s) and select Uninstall, and check the box that says 'Delete the driver software for this device'
above posted by Syncore - source http://forums.guru3d.com/printthread.php?t=371852
restart windows and install Catalyst driver; windows will need to restart and boot back into windows [allow this]
shut down the PC power down the PSU [wait for a couple of minutes], then install the Powercolour HD 6950 [*Do Not Install the crossfire bridge at this stage] attach the power cables
power up the PSU, boot into windows and allow windows to install the driver for the new hardware, next: restart and boot back into windows
Shutdown windows ; power down the PSU [wait for a couple of minutes] then install the Crossfire Bridge
Power up the PSU, boot into windows; goto catalyst control center and select crossfire
Install latest version of CAPS available here - http://sites.amd.com/us/game/downloa...n_win7-64.aspx
hope this helps