I have just purchased new RAM for my PC identical to my current RAM in everyway. This is as far as i can tell Corsair ValueSelect VS512MB400C I currently have 1gb of ram and iam trying to upgrade to 2gb of ram. I have 4 ram "slots" in my motherboard and i plugged in the 2 new RAM sticks the motherboard. The PC will not boot up with the extra ram in it. It doesnt even reach dos. It just does nothing. I then tried just the new RAM alone and it worked in place of the previous RAM. But when i exceed 1gb of ram the pc will not boot. My pc spec is Pentium 4 3.2Ghz Nvidia 6600 GT 128MB graphics card 1024 DDR RAM Windows XP Iam unsure how to determine what motherboard i have and i cannot find any marking or serial code on it. However i suspect this is a software error or some sort of RAM cap as iam pretty sure that a pentium 4 can handle more than 1gb or ram. Please help.