Laptop makes a clock like ticking noise?

Hey, So I have a 3 year old dell inspiron 15 3521 laptop. I've had to replace the hard drive as the laptop decided to freeze on me. I replaced it with another hard drive and again same problem. My cmos battery is loose. I've powered it on and it still makes that same clock like heart beat sound. I've got a recording of the sound but don't think I can post it haha.