Already got the issue in the past on my Asus P6T Deluxe V2, solved it and forgot about it. But a recent Clear CMOS operation (to retrieve full USB 2.0 ports that were somewhat downgraded to 1.1, weird issue) brought it to light again.
After checking this post High Pitched Noise Coming From Vertex 2 60GB SSD, it became apparent it is due to an energy saving option in the bios.
Disabled C1E Support and all is fine now!