First, my system has an Intel Core 2 Duo E6600 processor, a Gigabyte GA-965P-DS3 motherboard (I've also tried an ASUS P5N-E SLI mobo with same issue), and a Creative Sound Blaster X-Fi XtremeGamer (also tried an Audigy 2 ZS, same issue).

It took a while - a couple of months, approximately - to get this far, but I've finally found an interesting aspect of this problem.

But first, what's the problem? The problem for me is that when playing videos or certain types of audio it will often "skip-forward", or ahead in playback position, leaving out a chunk of audio from about 350 milliseconds to a second, or "missing a beat". It ONLY happens with my Creative sound cards; it does not happen with onboard sound. And it only happens when using DirectSound, which happens to sound the best.

I'd tried everything; BIOS settings, changing IRQs, disabling ACPI (well, at least I think I tried that), reinstalling Windows, disabling startup programs and services.. and, of course, I tried different codecs and media files. It mainly happens in videos (AVI, MKV), but happens in certain contained formats such as Matroska audio as well.

Eventually I tried messing with the Processor Affinity option in Windows' Task Manager. It turned out that if the video player was running on "CPU 0" alone and not on CPU 1, it would work fine and there were no skips. But if it was running on CPU 1 or both, it would skip. Randomly, of course. A couple per hour at most, but still annoying.

This is a valid workaround, then - so is disabling hardware acceleration (or setting it to Basic) or using WaveOut instead of DirectSound (from what I've heard), but it's a pain to have to change the processor affinity all the time and I was still curious why this problem was happening.

The Windows Server 2003 Resource Kit Tools comes with an Interrupt-Affinity tool, which basically allows you to set which core/CPU that interrupts for a specific device are sent, from how I understand it. So I tried setting my Sound Blaster's affinity to CPU 1, and guess what effect it had?

This reversed the problem. CPU 0 became the skipping one, and CPU 1 became flawless.

What does this suggest? Is there anything I can do to correct this, some sort of setting I can change, fix I can install...? Could there be a problem with my power supply, motherboard (even though I've already replaced it), BIOS settings, etc. that I'm overlooking? It's a strange issue, but it seems limited to this new dual-core system of mine. Let me know if you have the same or similar issues.

Any ideas or thoughts? Thanks,
SireeBob