I am attempting to install a AMD Radeon 6450 graphics card on my sister's Dell Optiplex 780 with an Intel Core 2 Duo E8600. I am struggling to get the display working. The monitor simply says "Check Video Cable".
I have attempted to download drivers both from here and here. The former (provided by Dell) seemed to install fine, but did not fix the issue. The latter, seems to rely on detecting the hardware (even if I do the manual selection). Unfortunately, this will not work. If I install the Radeon card physically, I get no display (the PC seems to favor the Radeon over the stock/integrated graphics), so I cannot run the installer/detection program with the card actually in the computer. The BIOS only has two options, Auto and some other option (I cannot recall the exact label). I have tried both with the same result (no display when the Radeon is installed).
Any advice would be appreciated. The machine is running Windows 7 64 bit. Thanks.