garageCube

If I have my MAC on with a decklink card and turn off one out four projectors all the output signals scramble and the outputs change. Is there a way to lock the outputs?

Could you describe the problem with more details and proper sentences, please. Like what mac, what deckling card, what about the projectors, what do you mean by scramble,how outputs change. Thanks!
And do not double post. The answers may get badly scattered all over.

try switchresx

the problem are the dvi edid signals. you might want to try a edid manager. this will make the mac believe there is still a output connected even though there is none.

google for

gefen dvi detective
lightware edid manager