"peee" sound when 5.1 on

[thelastdrone]

Greetings, iv been having this squeaky "peeeeeeeeeeeeee" like sound coming from my HDD when i use my 5.1 speakers (Stereo=no peeeeeeee).
On-board Realtek HD sound, iv been experiencing it since i use vista and my on-board sound (ditched my SB was kinda crappy with vista)
New drivers, tried different settings from the Realtek Audio panel but it doesn't fix it.
Any ideas ?