I recently swapped out my 5770 for a 7850, before this I uninstalled my ATI Drivers, ran driver sweeper, then installed the new drivers. But when I plugged the new card in it doesn't appear to be recognised. It is connected to my monitor via VGA Cable with a DVI adapter, but whenever I plug card end of the cable into a DVI port either on the card itself or on the motherboards DVI port the monitor will sit in Power Saving mode. The only way to actually see the display to remove the adapter and run VGA/VGA. So far I have reseated the card, used a different adapter and enabled PCIE first in the BIOS but nothing has solved this problem.
The monitor is an LG Flatron W2242S should it matter.