diff --git a/src/i830_crt.c b/src/i830_crt.c
index d8e4a76..0e8319f 100644
--- a/src/i830_crt.c
+++ b/src/i830_crt.c
@@ -397,6 +397,7 @@ i830_crt_detect(xf86OutputPtr output)
     xf86OutputStatus	    status;
     Bool		    connected;
 
+    OUTREG(ADPA,  INREG(ADPA) & ~ADPA_DAC_ENABLE);
     /*
      * Try hotplug detection where supported
      */