According to the report, which can be seen here, Creative said that when it looked at the PCI bus on the nVidia nForce 4 motherboards when the crackle symptoms happened the Soundblaster X-Fi card PCI bus master memory requests for audio data were held off for ages.
There were apparently peak hold-offs of up to two milliseconds in some cases, which is unusual chipset behaviour at the best of times.
It is certainly "beyond the ability of a hardware audio accelerator to compensate for in its internal buffering".
Creative claims that the nForce 4 motherboard is the first motherboard on which these extremely long PCI service holdoffs have been observed by Creative.
However, Nvidia's Technical Marketing Manager, Sean Cleveland has responded in a Bjorn3D chat that the comment is pants and there were no open bugs regarding Creative's X-Fi audio card on Nvidian kit. µ
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