Hard drive noise/interference in studio monitors

Has anyone else experienced this? I built my system primarily for music production, so this is extremely frustrating. I'm using an RME Babyface USB audio interface + Yamaha HS80Ms with my CustoMac and can hear electronic interference (hard drive noise?) in the monitors when playing audio. There is no hum - only the crackling interference. The same occurs when using an Mbox 2 or Lexicon Alpha. I have tested all three interfaces with my MacBook Pro (with/without AC adapter connected) and I do not hear any noise in the monitors. The problem occurs when playing any kind of audio (streaming from internet or session on local drive). I dual-boot my system and I also experience this in Windows 7.

The system is an i7 2600K + Gigabyte Z68XP-UD4 (in a Corsiar Obsidian 550D, if that's important). I am currently using the motherboard USB ports for my interface (I have tested all of them with the same result). Would a separate PCI USB card make a difference? The system and monitors are all connected to the same surge protector. I'm running out of ideas!

Hi...
We are in the same boat, even i have experienced this noise problem too
If you are getting noise from RME , Mbox2 and from both mac and windows, IMO clearly its a hardware problem...
If the noise is corresponding to the HDD, Mouse or CPU activity ... there might be a ground loop occurring some where between your audio interface, monitors and the common ground terminal inside your computer cabinet.
I suggest you to shutdown the computer and disconnect all the cables and rewire everything(check all your cables are working fine), and also make sure you have a good ground to your cabinet. If there is no ground then wind a thin metal conductor(thin wire) to any of your motherboard screws to the metal surface of your cabinet. This should establish a good ground contact.....connecting the wire to the cabinet worked for me. And all the noise is gone... Hope this helps...
Cheers

had same issue with different setup - the noise floor reacted to CPU activity and graphic movement on screen... it was ground loop... my USB AUDIO INTERFACE had a cable running from HEADPHONE OUTPUT into a external passive headphone splitter... when i disconnected this splitter and connected my headphones directly to USB AUDIO INTERFACE HEADPHONE OUTPUT - DEAD SILENT... the splitter box was picking up some ground loop and feeding it backwards into motherboard through the USB INTERFACE headphone jack... the computer than amplified the noise and made it REACT to various activities on the PC (mouse movement, opening closing certain plugin GUI windows, moving cursor across the screen) it was weird but all resolved by removing an external headphone splitter box...

the giveaway is that when i touched the USB ports on the PC backpanel the noise changed or lowered significantly - my body was acting as grounding lead...

more here: http://www.tonymacx86.com/threads/apogee-duet1-usb-noise.197506/