I have a MSI K9VGM-V motherboard with a 512MB stick of Comstar DDR II PC2 5300 memory. I went to add an additional 1GB stick of Comstar DDR II PC2 5300 memory and now the PC will not perform POST. If I take out the 512MB stick the computer boots up fine. I've tried mix matching every senerio and I can not get this PC to perform POST with both sticks of RAM in?? I could see this happen if it was RAM made from two different manufactures but the RAM is identical except for the size difference. Any ideas what could be causing this?