I've just found what looks like it could be the answer in the form of Soft-15KHz but I've no idea what this EDID dongle is all about
Basically the dongle looks like this...


All it does is hook up a simple IēC EEPROM to the DDC Pins.
Now the VGA can get EDID Data from the dongle.
Actually I still build them on request as of now there basically was no "big" need for them. I've build about 20 pcs over the last two years.
Thats why you can't find them in any shop.
Fact is, NVidia doesn't seem to know what they want...
There is a "safe mode" for pre-DDC (non EDID capable) displays.
The OLD drivers (like 66.93 to 91.47) didn't have this safe mode at all.
The frist drivers with GeForce 8 support (don't remember the revision) added the safemode for GeForce 8 and newer cards but NOT for the older ones.
The current drivers (192.xx) seem have this safemode enabled for every chip generation...
Somewhere in between the safemode was gone completely...
So what does this "safe mode"?
Actually it limits the card to a hand full of resolutions (640x480, 800x600, 1024x768, each at 60Hz).
Some driver revisions allow other modes too, but output them in "safe" 31-48kHz.