Sounds like a RAM error. Try running single stick if you have two, and perhaps different slots. And of course you should check any other connection as well, but I do beleive that's a pretty typical RAM beep...
What make and model board do you have there? The type of bios whether Phoenix, Award, AMI, or other will have a description for the audio code heard that being the type. One place to see which bios version uses a particular code is seen at http://www.computerhope.com/beep.htm#4
For Award that would be ram as seen there. For AMI you have to count how many short beeos in a row you hear. Phoenix has 1-1-1-3 as verify real mode seen there. T_O_O is correct on examining all connections as well as trying each dimm separately. It's also possible one or dimms isn't seated down properly triggering the audio alert. try reseating each one as you run them separately. That will show if you have any bad ram or simply needed to reseat at least one dimm.