Crackling sound and distortion [it was the PSU]

[Nerdanel]

I can play sound on my computer, but it is distorted and accompanied by crackling. I use ALSA, and the problem persists with all the different audio-producing programs I have tried, from the KDE startup sound to aplay. Low notes are distorted more than high notes. If the speakers are on, I hear crackling and a faint, high whine even when nothing is being played. I have played with mixer settings and they are not at fault. It's not a speaker problem either. This problem appeared quite suddenly some time ago, possibly caused by a software update, but I'm not sure which update. I've tried recompiling everything, downgrading ALSA, and upgrading to a new kernel, but nothing has worked.

aplay -l:

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**** List of PLAYBACK Hardware Devices ****       
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
  Subdevices: 1/1                                                     
  Subdevice #0: subdevice #0                                          

cat /proc/asound/cards:

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 0 [Intel          ]: HDA-Intel - HDA Intel
                      HDA Intel at 0x90320000 irq 22
 1 [VirMIDI        ]: VirMIDI - VirMIDI
                      Virtual MIDI Card 1

cat /proc/asound/devices:

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  0: [ 0]   : control
  1:        : sequencer
 16: [ 0- 0]: digital audio playback
 24: [ 0- 0]: digital audio capture
 32: [ 1]   : control
 33:        : timer
 40: [ 1- 0]: raw midi
 41: [ 1- 1]: raw midi
 42: [ 1- 2]: raw midi
 43: [ 1- 3]: raw midi

The relevant part of lspci -v:

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00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 02)
        Subsystem: Intel Corporation Device 2113                                         
        Flags: bus master, fast devsel, latency 0, IRQ 22                                
        Memory at 90320000 (64-bit, non-prefetchable) [size=16K]                         
        Capabilities: [50] Power Management version 2                                    
        Capabilities: [60] MSI: Enable- Count=1/1 Maskable- 64bit+                       
        Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00              
        Capabilities: [100] Virtual Channel <?>                                          
        Capabilities: [130] Root Complex Link <?>                                        
        Kernel driver in use: HDA Intel                                                  

cat /proc/interrupts:

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           CPU0       CPU1
  0:         46          0   IO-APIC-edge      timer
  1:       6053          0   IO-APIC-edge      i8042
  4:          2          0   IO-APIC-edge
  9:          0          0   IO-APIC-fasteoi   acpi
 12:     182043          0   IO-APIC-edge      i8042
 16:     110101          0   IO-APIC-fasteoi   uhci_hcd:usb3, i915@pci:0000:00:02.0
 17:       4185          0   IO-APIC-fasteoi   pata_marvell
 18:      32274          0   IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb7
 19:     239112          0   IO-APIC-fasteoi   ata_piix, ata_piix, uhci_hcd:usb6
 20:     179901          0   IO-APIC-fasteoi   eth0
 21:          0          0   IO-APIC-fasteoi   uhci_hcd:usb4
 22:      16571          0   IO-APIC-fasteoi   HDA Intel
 23:      32277          0   IO-APIC-fasteoi   ehci_hcd:usb2, uhci_hcd:usb5
NMI:          0          0   Non-maskable interrupts
LOC:    4763215    4763188   Local timer interrupts
SPU:          0          0   Spurious interrupts
PMI:          0          0   Performance monitoring interrupts
PND:          0          0   Performance pending work
RES:      23962      47521   Rescheduling interrupts
CAL:       2140       7485   Function call interrupts
TLB:      14040      12045   TLB shootdowns
TRM:          0          0   Thermal event interrupts
THR:          0          0   Threshold APIC interrupts
MCE:          0          0   Machine check exceptions
MCP:         53         53   Machine check polls
ERR:          1
MIS:          0

Trying to change the sample rate (or do anything) with iecset results in the following:

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control "IEC958 Playback Default" (index -1) not found

[b0nafide]

Have you tried booting a livecd to test your sound with a different operating system?

[Nerdanel]

I booted to a live cd and reproduced the issue. It looks like this is a hardware problem. Since I know the speakers are fine, this leaves the integrated soundcard. Argh!

Though, I'm worried that it's not a hardware problem at all but some obscure ALSA auto-configuration bug. Can I be absolutely sure where the problem lies before going shopping for a stand-alone soundcard/new motherboard/new motherboard AND processor AND memory? I already bought new speakers (granted, my old speakers were very old), but that did nothing...

[Nerdanel]

For the interests of posterity, I'd like to announce that my integrated soundcard turned out to be completely fine but my power supply was drawing its last. Unclear power supply errors strike again! You might remember (but probably don't) that my earlier mysterious Xorg freezes turned out to be power supply related too.