"Am using Sony LCD monitor at moment with a HD15 connection. Earlier I was using an older NEC Multisync with same connection. Both monitors produce the same problem. I will try to describe." I have one suggestion. Try using a digital display with an adapter, instead of using the VGA adapter with your current monitors. It may be a problem with the way that connection is working with your graphics card. If the digital display works then you'll either have to get that or get a different graphics card. I'm pretty sure you could get an equivalent card for pretty cheap now.