diff --git a/OSBindings/Mac/Clock Signal/CSAtari2600.mm b/OSBindings/Mac/Clock Signal/CSAtari2600.mm
index 90f1596c0..df8059f22 100644
--- a/OSBindings/Mac/Clock Signal/CSAtari2600.mm	
+++ b/OSBindings/Mac/Clock Signal/CSAtari2600.mm	
@@ -24,23 +24,39 @@ struct Atari2600CRTDelegate: public Outputs::CRT::CRTDelegate {
 
 	dispatch_queue_t _serialDispatchQueue;
 
-	int _failedVSyncCount;
+	int _frameCount;
+	NSTimeInterval _startTimeInterval;
+	BOOL _didDecideRegion;
 }
 
 - (void)crtDidEndFrame:(CRTFrame *)frame didDetectVSync:(BOOL)didDetectVSync {
 
-	if(!didDetectVSync)
+	if(!_didDecideRegion)
 	{
-		_failedVSyncCount+=2;
-
-		if(_failedVSyncCount == 60)
+		if(_startTimeInterval < 1.0)
 		{
-			_atari2600.switch_region();
+			_startTimeInterval = [NSDate timeIntervalSinceReferenceDate];
+		}
+		else
+		{
+			_frameCount++;
+
+			if(_frameCount > 30)
+			{
+				float fps = (float)_frameCount / (float)([NSDate timeIntervalSinceReferenceDate] - _startTimeInterval);
+
+				if(fabsf(fps - 50.0f) < 5.0f)
+				{
+					_atari2600.switch_region();
+					_didDecideRegion = YES;
+				}
+
+				if(fabsf(fps - 60.0f) < 5.0f)
+				{
+					_didDecideRegion = YES;
+				}
+			}
 		}
-	}
-	else
-	{
-		_failedVSyncCount = MAX(_failedVSyncCount - 1, 0);
 	}
 
 	BOOL hasReturn = [self.view pushFrame:frame];
diff --git a/Outputs/CRT.cpp b/Outputs/CRT.cpp
index 7a77a90f2..9bd2a50fd 100644
--- a/Outputs/CRT.cpp
+++ b/Outputs/CRT.cpp
@@ -28,7 +28,7 @@ void CRT::set_new_timing(unsigned int cycles_per_line, unsigned int height_of_di
 	height_of_display += (height_of_display / 20);  // this is the overrun area we'll use to
 
 	// store fundamental display configuration properties
-	_height_of_display = height_of_display + 10;
+	_height_of_display = height_of_display;
 	_cycles_per_line = cycles_per_line * _time_multiplier;
 
 	// generate timing values implied by the given arbuments
@@ -103,7 +103,7 @@ CRT::SyncEvent CRT::get_next_vertical_sync_event(bool vsync_is_requested, unsign
 
 	// will an acceptable vertical sync be triggered?
 	if (vsync_is_requested && !_is_in_vsync) {
-		if (_sync_capacitor_charge_level >= _sync_capacitor_charge_threshold){// && _rasterPosition.y >= (kCRTFixedPointRange * 7) >> 3) {
+		if (_sync_capacitor_charge_level >= _sync_capacitor_charge_threshold && _rasterPosition.y >= (kCRTFixedPointRange >> 1)) {
 			proposedSyncTime = 0;
 			proposedEvent = SyncEvent::StartVSync;
 			_did_detect_vsync = true;
@@ -112,12 +112,12 @@ CRT::SyncEvent CRT::get_next_vertical_sync_event(bool vsync_is_requested, unsign
 
 	// have we overrun the maximum permitted number of horizontal syncs for this frame?
 	if (!_is_in_vsync) {
-		unsigned int time_until_end_of_frame = (kCRTFixedPointRange - _rasterPosition.y) / _scanSpeed[0].y;
-
-		if(time_until_end_of_frame < proposedSyncTime) {
-			proposedSyncTime = time_until_end_of_frame;
-			proposedEvent = SyncEvent::StartVSync;
-		}
+//		unsigned int time_until_end_of_frame = (kCRTFixedPointRange - _rasterPosition.y) / _scanSpeed[0].y;
+//
+//		if(time_until_end_of_frame < proposedSyncTime) {
+//			proposedSyncTime = time_until_end_of_frame;
+//			proposedEvent = SyncEvent::StartVSync;
+//		}
 	} else {
 		unsigned int time_until_start_of_frame = _rasterPosition.y / (uint32_t)(-_scanSpeed[kRetraceYMask].y);