It should change on it's own. You have to have to have the display connector (VGA, HDMI, DVI-I) connected to the gpu. https://www.google.fi/search?biw=1920&bih=949&tbm=isch&sa=1&ei=slg2WsumOYOukwWU_4LoCg&q=pc+with+gpu+back&oq=pc+with+gpu+back&gs_l=psy-ab.3...1508.6211.0.6460.7.7.0.0.0.0.128.707.0j6.6.0....0...1c.1.64.psy-ab..1.0.0....0.dJGxb8ZcO3U#imgrc=5HXFcTbgFIsCbM: