I've asked four questions now so I'm out of hints. Excuse this question for it's vagueness... Why the hell is my sound card emitting this high pitched squeal when I run it through a mixer with a USB sound card also running through the mixer from the same computer. For reference of past attempts, I've asked four questions trying to get to the bottom of this problem:

  1. Stereo and mono cables and jacks? What happens when you cross them?
  2. What is the difference between a balanced and unbalanced mono jack?
  3. Does a USB Isolator work any different than a powered single-port USB Hub?
  4. Source of ground looping? Different ground for USB and laptop's line out?

I feel like I've learned everything that I need to know about audio equipment and none of it was relevant. I've even updated my BIOS!!! For reference, here are some of the system specs,

BIOS Information
    Vendor: LENOVO
    Version: 6DET71WW (3.21 )
    Release Date: 12/13/2011

System Information
    Manufacturer: LENOVO
    Product Name: 746643U
    Version: ThinkPad X200s

Intel(R) Core(TM)2 Duo CPU     L9600  @ 2.13GHz

Here is the lspci info from the sound card:

00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)

Here is the lsusb info from my USB DAC:

Bus 006 Device 003: ID 08bb:2902 Texas Instruments Japan PCM2902 Audio Codec

Here is what dmesg outputs from the syslog when I plug it in:

new full-speed USB device number 3 using uhci_hcd
New USB device found, idVendor=08bb, idProduct=2902
New USB device strings: Mfr=1, Product=2, SerialNumber=0
Product: USB Audio CODEC 
Manufacturer: Burr-Brown from TI              
input: Burr-Brown from TI               USB Audio CODEC  as /devices/pci0000:00/0000:00:1d.0/usb6/6-2/6-2:1.3/input/input13
hid-generic 0003:08BB:2902.0002: >input,hidraw0: USB HID v1.00 Device [Burr-Brown from TI               USB Audio CODEC ] on usb-0000:00:1d.0-2/input3

I already know the answer to this.. I've spent three days researching the problem and I want this to be out there for others to find.

  • So - you have one other question on this topic number 4 in your list. Can you answer that one as well, or do you want to merge the questions? (Your other 3 are unconnected to this issue)
    – Rory Alsop
    Nov 1, 2012 at 20:59
  • They're all unconnected, no one who isn't experienced with this problem would have guessed that power regulation for the CPU was interfering with onboard and USB DACs Nov 1, 2012 at 21:17
  • Also, I think #4 is a valuable question even if unrelated. I'd be curious to know the answer. I'll leave it up for bit. Nov 1, 2012 at 21:18
  • Isn't the answer exactly the same though? You have found the cause of the issue. (And it was nothing that I would have expected :-)
    – Rory Alsop
    Nov 1, 2012 at 21:20
  • I'm inclined to wait, I still want to know more about ground. I've read there are numerous ways to make a fake ground but does the ground for audio (3.5mm out) share the same fake ground as USB in? Nov 1, 2012 at 21:35

1 Answer 1


For some reason Lenovo X200s and X201 have a problem with this. It's probably just specific to the Core 2 chipset:

Intel(R) Core(TM)2 Duo CPU L9600 @ 2.13GHz

BIOS with disabled power management

Anyway, simply disable all power management functionality in the BIOS. It will all cause a draw on something and result in high pitched audio fluctuation. Others with a Core2 have complained about this too.

Lenovo says this about the problem on a different product.:

Due to tolerances, the capacitors in some systems may resonate at high frequencies as the CPU's C-states change. Not all systems will emit these sounds, and due to differences in environment, background noise, and individual user hear acuity, they may not be noticable. This is considered a normal phenomena. Some customers have reported success using ThrottleStop to limit CPU fruquency changes..

Different users report this problem with everything from USB DACs, to USB Headsets -- just about anything audio with USB.

Here are some other computers that are plagued with this problem:

You can find numerious reports of this problem on Tom's Hardware or even on the Intel forums. Many describe this as a whine.

  • I'd like to point out if Intel wasn't so predisposed obsessing over the environment and other pointless things, my sound would have worked fine. Nov 1, 2012 at 7:10
  • 2
    Keep in mind that Intel's 'pointless' obsession with the environment is what keeps your lap from catching fire. Also, in a modern office building, the heat generated by IT gear can put a significant load on the HVAC system, adversely impacting your comfort in the office. (I've had to sign off on six-figure capital expenditures to mitigate the heat generated by the computers required by a smallish A/V editing team!) Nov 1, 2012 at 8:13
  • 1
    Great and to think I thought they were in the business of making processors, apparently all they do is design HVAC workarounds and sell them to me as CPUs. Nov 1, 2012 at 8:33
  • it is probably an unvarnished coil resonating and not the cpu at all. Many graphics cards have this same problem under heavier loads.
    – horatio
    Nov 1, 2012 at 14:26
  • 1
    Anyway, great find. It's great that you got to the bottom of the problem! ... the very very bottom :)
    – JoshP
    Nov 1, 2012 at 20:14

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