Hey, i made the mistake of buying a second hand Samsung 500GB 7200rpm HDD [3GB/s SATA 2] and it boots up slower than my old 150GB WD 1.5GB 5000rpm, but that's not the point. What is happening is that when booting the pc up it makes a high pitched noise, but the weird part is it doesn't do that on any boot, only after the system has been inactive for a period of time [usually in the morning, after it's been off for around 10 hours]. Should i worry? It doesn't whistle while using it, only on boot up for around 10 seconds, then it stops.