I tried the beta
driver and it did not solve the problem. Creative seems to think this is the problem:
Technical Details
We have observed through direct observation of the PCI bus on the nVidia nForce 4 motherboards that when the crackle symptoms are occuring, the Sound Blaster X-Fi card PCI bus master memory requests for audio data are being held off (not serviced) for very long intervals.
We have observed peak holdoffs of up to 2 milliseconds in some cases. This is unusual chipset behavior that is beyond the ability of a hardware audio accelerator to compensate for in its internal buffering. The Sound Blaster X-Fi tolerance for these PCI holdoffs is approximately 120 microseconds peak holdoff, with a 1 microsecond average holdoff.
These design tolerances are based on observation of real PCI bus behavior on leading motherboards over a period of many motheboard hardware generations.
The nForce 4 motherboard is the first motherboard on which these extremely long PCI service holdoffs have been observed by Creative, where another PCI device in the system was not causing the holdoff.
Not sure how to fix this issue.