I have a D945GTP motherboard. I populated it with 4 pcs of 1GB DDR2/800 memory total 4GB. the system will boot up without the video card (ATI X1600PRO) and using the onboard video. If I install the video card, the system boots up but no display, not even a beep. I know it is booting up because the Hard drive activity light is blinking. I tried another video card and the same problem. If I use only 2GB of memory (2 pcs. 1GB), it will boot up using the ATI video card. Need help !!!