I have same thing with my Samsung monitor, but I wouldn't call it a problem, just use your native resolution! It happens because DVI cable transfers video information in pixels, which means 1 pixel from the card gets 1 pixel on the monitor. If you're using lower than native resolution, your screen will be smaller. Some monitors have option to stretch it, and some don't. The only solution I can offer you if your monitor doesn't have that option is either use native resolution, or, if you cannot do that for some reason, use D-SUB (also known as VGA) cable. It doesn't map pixels 1:1, so stretching is automatic.