Buzzing/hissing sound through speakers at Windows start screen

I am having a major problems with a high pitched beeping/cracking/hissing sound coming from my speakers. The sound starts about halfway through the Windows startup screen. The system is the workstation in my signature.

The speakers are powered studio monitors and do not make the sound with any other source and I have even tried using the same wiring and power with the computer running but using my phone as a source to eliminate any local EMI source.

Thinking there might be a problem with my sound card, I tried the onboard audio controller and a Fiio E17 USB DAC. The problem persisted with all 3 sound sources.

Within the system I have removed all the hard drives, DVD drive, every PCI/PCIe card except 1 graphics card (have tried leaving both in the system in different slot). I have also disconnected all but the essential fans on my CPU, 260GTX, and PSU. So all that is left in the system is the CPU (stock speeds), 1 stick of RAM, SSD, and PSU. While I was in there, I thoroughly dusted everything, not that it was particularly dirty.

Windows 8 and all hardware drivers are up to date and there is no system instability.

However, when I opened the case and disconnected some extra fans, I noticed that I could hear the same buzzing noise that is emanating from my speakers even with my speakers disconnected. It sounds like it is coming from the CPU area of the motherboard. Thinking it might be a power regulating problem, I turned off SpeedStep in the BIOS and disabled all CPU power control in Windows. Needless to say, that didn't help either.

Also, I have noticed that if I hold down a key on my keyboard, the sound changes from a random collection of high pitched beeps, crackles, and hissing to a consistent, high pitched, high rate beepish sound.

It seems to me that it should be software based since it starts ate the exact same point about halfway through the Windows startup screen and does not start regardless of how long I leave the system in the BIOS settings. That leads me to think that its not just a capacitor charging and then complaining.

Any ideas?

Thanks in advance for the help!

Any ideas?

Is the CPU overclocked, have you tried stock speeds?

Have you tried booting Knoppix to confirm that it's a software issue?

The CPU is at stock speeds. I have played around with turning various onboard features on/off, but have been unable to find a configuration to eliminate the noise.

That is a good idea to try another OS....I will try that once I have a few free hours.

I tried hooking up my desktop to my receiver (desktop->hdmi->receiver-> preouts->RCA->Adam monitors) and did not have any problems. This is the only setup I have found so far to eliminate the buzzing. I am still a bit confused as to why the buzzing persists when I use a USB DAC. Perhaps everything that is powered through the motherboard is receiving the same noise signal. If this is the case, it is certainly concerning since my HDDs may also be getting the signal. I will try borrowing a multimeter from my lab to test the PSU to see if the noise is coming from it or being generated within the motherboard's circuitry. I am thinking probably within the motherboard with a software activated feature since the buzzing starts during the Windows Start screen and will not start no matter how long I leave the system idling in BIOS.

I would greatly prefer to use the hardware I have. My receiver is located in a different room for my HT, so if it comes to the point where I need a hdmi out, I will need to purchase a receiver. Unfortunately, I do not have any optical cables to try that connection easily.

I just tried Knoppix and while I also got some of the same sounds, the magnitude was much less. In Windows even with music playing it is blatantly obvious. In Knoppix, if I play music, I can hardly tell except during quiet parts. Again, the buzzing started while Knoppix was loading. Perhaps one of the drivers that is loaded during startup is causing the problem. I am thinking the next step will be to uninstall drivers and see if there is any improvement.

Might be a ground loop or excessively low signal levels. Try maxing out all the volume controls on your PC that seem to affect the music volume (but not go into "overboost") and using the volume control on the amp to make the actual volume adjustments. That should boost your SNR.

In the long term, you might want to upgrade to a digital amplifier/receiver.

I get that effect sometimes with some systems and it seems to be exacerbated in overclocked systems. But you're saying this still happens when you plug the speakers into your phone?

I tried maxing out the software volume and minimizing the amplifier volume and that made the problem bearable. Its not noticeable while listening to most music, but is still audible enough that I have to turn the speakers off while not listening.

The problem does NOT happen when I connect the speakers directly to my phone or my receiver, or my HTPC. In fact, the only way I can get clean audio out of this computer is via HDMI to my receiver. I have tried an external DAC connected via USB, and on battery power via coaxial connection, onboard audio, and through my fairly high end sound card.

My friend has an extra optical cable, so I am going to try that just to confirm that it will work since usb and coaxial did not.

Do you have any external devices plugged in to the input of your sound card? Sometimes the noise can be caused by a dirty signal going into the machine.

No inputs besides the power connection for headphone amplifier which is required for the card to function.