Beeping sound caused by RAM

Hi There!
My RAM (Random Access Memory) is not serve good service. Because sometimes it does not beep any sound.
Ans sometimes it is not respond.
I cannot tell what is the main and prime option. But I am sure it is the RAM option.
Sometimes my windows screen will be splahing like a fisheries ne and I cannot move my mouse cursor.
Then a little beep sound is creating inside my PC.
Why RAM makes a beep sound?
Just I know this good answer.
Thanks.
