The OP is referring to the 3-pin monitor ID on the original VGA connector, predating DDC standard two-way communication. He wants the card to think no monitor is connected thus using whatever is the default or Basic mode.
4 11 12
ID2 ID0 ID1
n/c n/c n/c no monitor
n/c n/c GND Mono monitor which does not support 1024x768
n/c GND n/c Color monitor which does not support 1024x768
GND GND n/c Color monitor which supports 1024x768
It seems to me 4, 11, and 12 would all have to be removed.
It's posts like this one that remind me we got some people that really seem to know their sheeeeot.