an update i have removed the GVP JAWS II turbo card and the RGB signal loaded from hard disk worked, the same with another amiga 1200 so itsnt a problem of the amiga. its a problem of ide and jaws II i think.
Sounds like a power issue imho, too much load.
Are you using the standard a1200 psu, or even an A500 one? You could try powering using an ATX psu and connecting to the power header for the floppy drive. I believe there is a -12V missing compared to the Amiga psu, but it shouldn't cause any problems in terms of testing the display with all the extra peripherals attached, just possible audio problems iirc.
If this does turn out to be the cause, you can always hack together an ATX-Amiga adapter using Steddy's
excellent guide.
Regards
Rich
