diff --git a/src/i830_lvds.c b/src/i830_lvds.c
index 639450a..228378d 100644
--- a/src/i830_lvds.c
+++ b/src/i830_lvds.c
@@ -69,6 +69,8 @@ struct i830_lvds_priv {
     enum pfit_mode fitting_mode;
     uint32_t pfit_control;
     uint32_t pfit_pgm_ratios;
+    uint32_t max_clock;
+    uint32_t min_clock;
 };
 
 #define BACKLIGHT_CLASS "/sys/class/backlight"
@@ -1280,6 +1282,15 @@ static const xf86OutputFuncsRec i830_lvds_output_funcs = {
 #endif
 };
 
+static Bool
+i830_lvds_valid_fixed_mode(struct i830_lvds_priv  *dev_priv,
+	                   DisplayModePtr mode)
+{
+    if (dev_priv->max_clock < mode->Clock ||
+	    dev_priv->min_clock > mode->Clock)
+	return FALSE;
+    return TRUE;
+}
 void
 i830_lvds_init(ScrnInfoPtr pScrn)
 {
@@ -1315,6 +1326,15 @@ i830_lvds_init(ScrnInfoPtr pScrn)
     dev_priv = (struct i830_lvds_priv *) (intel_output + 1);
     intel_output->dev_priv = dev_priv;
     
+    if (INREG(LVDS) & LVDS_B0B3_POWER_MASK) {
+	/* dual channel KHZ*/
+	dev_priv->max_clock = 224000;
+	dev_priv->min_clock = 80000;
+    } else {
+	/* single channel KHZ*/
+	dev_priv->max_clock = 112000;
+	dev_priv->min_clock = 20000;
+    }
     /*
      * Mode detection algorithms for LFP:
      *  1) if EDID present, use it, done
@@ -1343,6 +1363,8 @@ i830_lvds_init(ScrnInfoPtr pScrn)
      */
     modes = i830_ddc_get_modes(output);
     for (scan = modes; scan != NULL; scan = scan->next) {
+	if (i830_lvds_valid_fixed_mode(dev_priv, scan) == FALSE)
+	    continue;
 	if (scan->type & M_T_PREFERRED)
 	    break;
     }
@@ -1369,7 +1391,8 @@ i830_lvds_init(ScrnInfoPtr pScrn)
      * the BIOS being unavailable or broken, but lack the configuration options
      * for now.
      */
-    if (pI830->lvds_fixed_mode)
+    if (pI830->lvds_fixed_mode &&
+	    i830_lvds_valid_fixed_mode(dev_priv, pI830->lvds_fixed_mode))
 	    goto found_mode;
 
     /* If we *still* don't have a mode, try checking if the panel is already