Well I took Fordem's advice, and unplugged the ethernet cable. The device went into standby as usual, then probably 2 or so hours later, I heard it start up again. Funny thing is though, it only starts up one hard drive from what I can hear. So it's definitely internal, for some reason it's starting just one hard drive, accessing it briefly, then shutting down again after the set 30 minutes. Very strange...