Okay, so I built myself a computer and gave my old Dell Demension 8300 to my brother. I kept the hard drives, and, when he went to buy a new one, he got some extra RAM (DDR). Not being very technical himself, he called me over to help. We took an old pair of 256 meg sticks out and put in a new pair of Corsair 512's in. When we powered it on, it just beeped for a while and refused to send any output to the monitor. After some trial and error, we figured out that the board just doesn't like the Corsair RAM at all. I examined the sticks and found that the Corsair was CL2, while the set we had taken out was CL3. Other than that, it didn't' look like there was a major difference. Is this CL- difference the source of the problem?
Either your RAM isn't seated correctly or it's the wrong kind for your system.
If it happens to be the first issue simply remove the new RAM and reset it to ensure it has clicked into place. Another one you can try here is use one at a time to ensure one isn't faulty.
If you continue to get the beep tone you likely need new RAM. I suggest Crucial for your RAM. See here for a list of RAM for your system.