(1) find a latest non-beta driver for this card, install it, reboot and see if things improve,
(2) change pci latency values in bios. Try with 64 cycles. Save and Exit. Use your computer for some time and see if this helps. If you do not have this setting in bios you can google PCI latency timer tool, it is free.
(3) Another thing to try is to reinstal your "My computer" driver i.e. ACPI configuration in Device Manager. If it is currently listed as ACPI Uniprocessor try changing this to ACPI Advanced Configuration and Power Interface. Not sure why but it helps a lot with sound issues. But can't be done if you use hyperthreading or dual core. (Don't pick standard PC). Once it is done check the IRQ assigments again to make sure sound card's IRQ not shared.
(4) Try to observe what precedes or accompanies this stuttering
(5) Switch off all services loaded at startup in msconfig.exe (i.e use diagnostic startup) and disconnect from the web and see if problem occurs or not. If it does not then it is another clue.
I have the same problem but I do not have a sound card (just using whats on the mobo) my problem is I only get that noise whenever i open an application but not all the time i get it,,, my ??? is,, is that normal?