Noisy during boot up?

[helloworld]

Recently my computer has started to make terrible noises when I first boot it up. Its hard to explain but its like the noise of a disc scratching, it lasts for at least 5 minutes when I first boot up and then settles down. The computer is working fine, its just this darn noise whenever I turn it on.

Specs are:
Gigabyte P67A-UD3 Motherboard
Intel Core i5 2500K, Sandy Bridge @ 1.6Ghz - 3.3GHz with turbo on
4GB DDR3 Mushkin RAM
NVIDIA GTX 460 1GB graphics card
1TB SATA2 hard drive
Windows 7, Service pack 1, 64bit

Can anyone explain what could be causing this noise?

[deranjer]

My advice would be to start unplugging crap (HDD/DVD Drive) etc, until when you boot up the noise does not occur, that should narrow it down, also, unplug fans one at a time to see if it is a fan, make sure nothing is stuck in a fan (unlikely as the noise stops, but hey worth a shot).  As well, turn on PC with case open, then get down close to the MB and narrow down the noise.

[Dark Mantis]

deranger has the right approach and is the easiest way to find out what is causing it to be honest. It is most likely you hard drive on the way out and before you say it's only "x months old" that really doesn't make any difference. They can play up at any time. A fan is possible but I would go for the hard disk myself.