diff --git a/src/add-ons/accelerants/via/GetAccelerantHook.c b/src/add-ons/accelerants/via/GetAccelerantHook.c
index e19ad43861..dcd777eba1 100644
--- a/src/add-ons/accelerants/via/GetAccelerantHook.c
+++ b/src/add-ons/accelerants/via/GetAccelerantHook.c
@@ -90,15 +90,15 @@ void *	get_accelerant_hook(uint32 feature, void *data)
 		*/
 
 		/* only export video overlay functions if card is capable of it */
-//		CHKO(OVERLAY_COUNT);
-//		CHKO(OVERLAY_SUPPORTED_SPACES);
-//		CHKO(OVERLAY_SUPPORTED_FEATURES);
-//		CHKO(ALLOCATE_OVERLAY_BUFFER);
-//		CHKO(RELEASE_OVERLAY_BUFFER);
-//		CHKO(GET_OVERLAY_CONSTRAINTS);
-//		CHKO(ALLOCATE_OVERLAY);
-//		CHKO(RELEASE_OVERLAY);
-//		CHKO(CONFIGURE_OVERLAY);
+		CHKO(OVERLAY_COUNT);
+		CHKO(OVERLAY_SUPPORTED_SPACES);
+		CHKO(OVERLAY_SUPPORTED_FEATURES);
+		CHKO(ALLOCATE_OVERLAY_BUFFER);
+		CHKO(RELEASE_OVERLAY_BUFFER);
+		CHKO(GET_OVERLAY_CONSTRAINTS);
+		CHKO(ALLOCATE_OVERLAY);
+		CHKO(RELEASE_OVERLAY);
+		CHKO(CONFIGURE_OVERLAY);
 
 		/*
 		When requesting an acceleration hook, the calling application provides a
@@ -170,8 +170,11 @@ status_t check_overlay_capability(uint32 feature)
 		break;
 	}
 
-	/* all supported cards have a bes */
-	LOG(4, ("Overlay: Exporting hook %s.\n", msg));
+	/* all supported cards have a bes, but it can't always be used... */
+	if (eng_bes_chk_bandwidth())
+		LOG(4, ("Overlay: Exporting hook %s.\n", msg));
+	else
+		LOG(4, ("Overlay: Not exporting hook %s.\n", msg));
 
 	return B_OK;
 }
diff --git a/src/add-ons/accelerants/via/engine/bes.c b/src/add-ons/accelerants/via/engine/bes.c
index b0fe8cf442..5244ab93f8 100644
--- a/src/add-ons/accelerants/via/engine/bes.c
+++ b/src/add-ons/accelerants/via/engine/bes.c
@@ -19,6 +19,64 @@ struct move_overlay_info
 static void eng_bes_calc_move_overlay(move_overlay_info *moi);
 static void eng_bes_program_move_overlay(move_overlay_info moi);
 
+/* returns true if the current displaymode leaves enough bandwidth for overlay
+ * support, false if not. */
+bool eng_bes_chk_bandwidth()
+{
+	float refresh, bandwidth;
+	uint8 depth;
+
+	switch(si->dm.space)
+	{
+	case B_CMAP8:        depth =  8; break;
+	case B_RGB15_LITTLE: depth = 16; break;
+	case B_RGB16_LITTLE: depth = 16; break;
+	case B_RGB32_LITTLE: depth = 32; break;
+	default:
+		LOG(8,("Overlay: Invalid colour depth 0x%08x\n", si->dm.space));
+		return false;
+	}
+
+	refresh =
+		(si->dm.timing.pixel_clock * 1000) /
+		(si->dm.timing.h_total * si->dm.timing.v_total);
+	bandwidth =
+		si->dm.timing.h_display * si->dm.timing.v_display * refresh * depth;
+	LOG(8,("Overlay: Current mode's refreshrate is %.2fHz, bandwidth is %.0f\n",
+		refresh, bandwidth));
+
+	switch (((CRTCR(MEMCLK)) & 0x70) >> 4)
+	{
+	case 0: /* SDR  66 */
+	case 1: /* SDR 100 */
+	case 2: /* SDR 133 */
+		/* memory is too slow, sorry. */
+		return false;
+		break;
+	case 3: /* DDR 100 */
+		/* DDR100's basic limit... */
+		if (bandwidth > 921600000.0) return false;
+		/* ... but we have constraints at higher than 800x600 */
+		if (si->dm.timing.h_display > 800)
+		{
+			if (depth != 8) return false;
+			if (si->dm.timing.v_display > 768) return false;
+			if (refresh > 60.2) return false;
+		}
+		break;
+	case 4: /* DDR 133 */
+		if (bandwidth > 4045440000.0) return false;
+		break;
+	default: /* not (yet?) used */
+		return false;
+		break;
+	}
+
+//fixme: temporary (implement overlay first)
+//	return true;
+	return false;
+}
+
 /* move the overlay output window in virtualscreens */
 /* Note:
  * si->dm.h_display_start and si->dm.v_display_start determine where the new
diff --git a/src/add-ons/accelerants/via/engine/proto.h b/src/add-ons/accelerants/via/engine/proto.h
index 117001a122..c4d990abae 100644
--- a/src/add-ons/accelerants/via/engine/proto.h
+++ b/src/add-ons/accelerants/via/engine/proto.h
@@ -115,6 +115,7 @@ status_t eng_acc_wait_idle(void);
 
 /* backend scaler functions */
 status_t check_overlay_capability(uint32 feature);
+bool eng_bes_chk_bandwidth(void);
 void eng_bes_move_overlay(void);
 status_t eng_bes_to_crtc(bool crtc);
 status_t eng_bes_init(void);