If it's an irregular 'ticking' noise, this may be the hard drive. Remove the hard drive from the top of the console (when powered off) and see if the problem goes away. Try your Xbox in both vertical (upright) and horizontal (flat) positions to see if it goes away (but don't move the console while it is on, or it will scratch any discs in the drive). If it's the DVD drive making the noise, it will probably need to be professionally repaired. If it's the hard disk, you could get another.
Touche, November 2010
