diff --git a/hw/xfree86/modes/xf86Crtc.c b/hw/xfree86/modes/xf86Crtc.c
index 9512805af..41ac2f6e0 100644
--- a/hw/xfree86/modes/xf86Crtc.c
+++ b/hw/xfree86/modes/xf86Crtc.c
@@ -1484,7 +1484,14 @@ xf86ProbeOutputModes (ScrnInfoPtr scrn, int maxX, int maxY)
 	}
 	default_modes = xf86GetDefaultModes (output->interlaceAllowed,
 					     output->doubleScanAllowed);
-	
+
+	/*
+	 * If this is not an RB monitor, remove RB modes from the default
+	 * pool.  RB modes from the config or the monitor itself are fine.
+	 */
+	if (!mon_rec.reducedblanking)
+	    xf86ValidateModesReducedBlanking (scrn, default_modes);
+
 	if (sync_source == sync_config)
 	{
 	    /* 
diff --git a/hw/xfree86/modes/xf86Modes.c b/hw/xfree86/modes/xf86Modes.c
index 2dff31b3a..3a9f3ff24 100644
--- a/hw/xfree86/modes/xf86Modes.c
+++ b/hw/xfree86/modes/xf86Modes.c
@@ -518,6 +518,28 @@ xf86ValidateModesBandwidth(ScrnInfoPtr pScrn, DisplayModePtr modeList,
     }
 }
 
+/**
+ * Marks as bad any reduced-blanking modes.
+ *
+ * \param modeList doubly-linked list of modes.
+ */
+_X_EXPORT void
+xf86ValidateModesReducedBlanking(ScrnInfoPtr pScrn, DisplayModePtr modeList)
+{
+    Bool mode_is_reduced = FALSE;
+    DisplayModePtr mode;
+
+    for (mode = modeList; mode != NULL; mode = mode->next) {
+	/* gratuitous duplication from pre-randr validation code */
+	if ((((mode->HDisplay * 5 / 4) & ~0x07) > mode->HTotal) &&
+	    ((mode->HTotal - mode->HDisplay) == 160) &&
+	    ((mode->HSyncEnd - mode->HDisplay) == 80) &&
+	    ((mode->HSyncEnd - mode->HSyncStart) == 32) &&
+	    ((mode->VSyncStart - mode->VDisplay) == 3))
+	    mode->status = MODE_NO_REDUCED;
+    }
+}
+
 /**
  * Frees any modes from the list with a status other than MODE_OK.
  *
diff --git a/hw/xfree86/modes/xf86Modes.h b/hw/xfree86/modes/xf86Modes.h
index 5d49c9314..acdea65d8 100644
--- a/hw/xfree86/modes/xf86Modes.h
+++ b/hw/xfree86/modes/xf86Modes.h
@@ -84,6 +84,9 @@ void
 xf86ValidateModesBandwidth(ScrnInfoPtr pScrn, DisplayModePtr modeList,
 			   unsigned int bandwidth, int depth);
 
+void
+xf86ValidateModesReducedBlanking(ScrnInfoPtr pScrn, DisplayModePtr modeList);
+
 void
 xf86PruneInvalidModes(ScrnInfoPtr pScrn, DisplayModePtr *modeList,
 		      Bool verbose);