I have gotten 4 of the SB bundled 8540w's with the docking stations and seem to be seeing an issue. I have update to the most recent bios that was post which was f.08 as well have updated all drivers. I don't think its a hardware issue totally but possibly might be.
All 4 of these suffer from stuttering sound. There isn't really anything installed on them except office 2010 and vmware 6.5 workstation and windows 7 x64. They were all installed fresh and not from some base image. On all laptops if you reboot the audio is fine but as the day wears on it will stutter. 2 laptops will stutter all audio all the time. the other 2 laptops only stutter low bitrate mpeg and mp3 audio.
I have plugged in a usb headset which adds its own soundcard driver and the problem carries over to that as well. So thats why I don't know if its really hardware related... I thought maybe a codec was causing the issue but there hasn't been any installed, so I tried klite codec pack on 1 and the fdshow tryout on another with the same results. But if i reboot its all good until a little later in the day. It's also totally random when it starts.
I found the problem to the audio stuttering which was causing the high latency. Intel(R) Management and Security Application User Notification Service - Updates the Windows Event Log with notifications of pre defined events received from the local Intel(R) Management and Security Application Device. if i disable the service the audio is fine. If i re-enable the service the problem re-appears. I think hp needs to log a bug with intel on it as well as putting it out there if others have a similar problem.
It may also be worth trying to disable the HP Power Assistant program from your list of running processes.