help with gu8 power and noise

[gowalkabout.com.au]

ok so the GU8 has just turned 1y/o and for a little while now there has been what sounds like an electical whine I have turned the stereo off and the noise is still there. anyway today it happened again and this time i put the window down and it sounded like the turbo was about to take off. I am just wondering if anyone else has had this happen? the sound seems to come and go and it dosn't seem to matter if the rig is hot or cold.