This is wierd as hell, never read anything about this...
Ever sicne I did my OC yesterday and started running some of the benchmarks I lost my sound...In the system menu says they are working properly but yet nothing...
First question, is your sound card onboard or is it a seperate card in a PCI slot? it looks like an onboard sound card from here however.
First thing lock both your PCI and AGP clocks, 33.3MHz for PCI and 66.6MHz for AGP. If you can't lock them at exactly these frequencies then clock them as close as possible. Lock them a little higher than these values, not a little lower if you can't get them exact.
As mentioned above in the thread this would be the most logical explaination for the problem in question.
However the PCI clock influences an onboard sound card much less than a PCI card, I am guessing that due to these higher clocks the PCI and AGP frequencies have gone much higher and may be interfering with some of the driver files for your sound card, thus there is no sound