Computer runs perfectly fine but motherboard keeps beeping.?

I've recently built a new computer, and I've installed Windows XP like normal while the motherboard kept beeping. So now, I pretty much have a computer that runs PERFECTLY fine, but the motherboard just keeps beeping and doesn't stop. The motherboard I have is an Aopen i945 gm PILF and it has a Phoenix BIOS. The beeping pattern is 2 different beeps like, 1-2-1-2 and etc... and keeps repeating over and over. What could be the problem?