nVidia 7300 gives black screens, Win7 will not load

Windows 7 Professional-64 bit, SP 1
nVidia GeForce 6200 - 256 DDR2 Driver 285.62
TYAN S2885 Thunder K8W
Dual processors: AMD Opteron 246 (2P) SledgeHammer 0.13um Technology
RAM: 8.0GB Dual-Channel DDR @ 199MHz
Dual Monitors: Acer-V223W (1680x1050@59Hz) eMachines E19T6W (1440x900@75Hz)
Board supports AGP8. In BIOS I allocated the maximum 512 memory aperture and enabled FastWrite
More details about my computer.docx
Here is the problem. The GeForce 6200 works pretty well with Windows 7 Basic theme but gets bogged down pretty fast if I use things like desktop gadgets or try to use Aero display. I attached the windows Performance rating file, showing the graphics at 2.0.
So I bought a used (eBay) BFG nVidia 7300 GT – 512 DDR2. After installing I downloaded and installed current nVidia driver (clean install). At that time it worked about equal to the 6200. So I tweaked a few settings (nope, don’t remember what all I did) then on restart I have black screens. Win7 would start, apparently normally; I entered my password, then after ‘loading your settings’ I have total black screens, no mouse, no taskbar, nada. I even gave it a couple of hours to move forward with no joy. For troubleshooting I went back to an old display card, just VGA on a single monitor and uninstalled all nVidia drivers, did registry cleaning with CCleaner, restarted a couple of times and repeated the purging of old drivers and settings. Then I reinstalled the 7300 card and…same result.
So now I am back to using the original 6200, exactly where I started.
I am guessing I have a setting somewhere that is asking the 7300 to do something both monitors are incapable of doing. I don’t know where it might be or how to get access to it.
I am hoping some of you graphics specialists and/or gamers can point me to effective troubleshooting steps. Please don’t bother telling me to get a new board; I am an old retired guy that has to make-do with what I have.

Try the 7300 in a different machine....if possible....might also try setting the memory aperture to the minimum setting....

Try this. Nvidia.pdf

Good ideas both, Thanks Ivan and Roderunner. I will post results