Hard Drive Constant Noise + Activity

I have 2 Spinpoint f3's (1tb each) in a Raid 0 array and 1 of them is constantly making noise and showing activity. The sound is as if something is writing to it but its not a constant write, it sounds like its in bursts. So it makes that noise every second. The strange thing is i can hear it only coming from 1 of the 2 hard drives and they are not even boot drives. They seem to run fine when I run applications off of them (games mostly) with no crashes, bsod etc.

So I'm not sure if its dying or something else.

I had some windows errors recently (that I fixed) from trying to put the pc to sleep mode and have been having slow boots ever since. I'm not sure if these are related. Seems unlikely due to the boot drive being an SSD and the problem having nothing to do with the HDD's.