PC start up (RAM)

Hi I have been getting a problem with my pc’s start up, when I switch it on it will start with no hassles, but as soon as I shutdown and want to start again the next day or an hour later the Beeps start. When it happens I turn of the pc remove one ram and insert it again and then the same with the other one. then it will start again. what could be the cause of that? I am using 2x transcend 1gig rams and even tried others. the motherboard is a gigabyte (don’t remember the spec’s, but its not new)?