Have you installed the latest Intel provided drivers? It sounds like you have bus contention issues, something often resolved with new drivers. Are ALL of your boards BIOS settings at default values (what you get when you choose the load BIOS default values option within the BIOS setup menu and save out of there)? Have you always experienced this since it was new or has it just arisen? I had high pitched squeeling from my DG45ID which a BIOS update went some way towards resolving so it'd be worth seeing if a newer BIOS version is available to address that (one of the pdf files on the download page explains the fixes in successive versions).