I’m using Windows 7 for two weeks now, and I immediately noticed that sometimes whenever a sound is played, it is preceeded by a loud popping noise.
After some research, I found the cause to be the sound chip power management on OS-level. It is all explained here.
Sorry I should have posted more detail.
The site that I got my information from was: Audio Device Class Inactivity Timer Implementation (Windows Driver Kit)
My “IdlePowerState” was set to 04, which is D3Cold in their terms; I changed it to 03 (which I assume is D3Warm, and which I also assume is the pre-Windows 7 setting); it made no difference. Since this is a desktop and not a laptop, I ignored the ConservationIdleTime setting (since that applies to running on battery power), and I increased toe PerformanceIdleTime from 012c (or in the registry, “2c 01 00 00″) which is 300 seconds, to “2c 0f 00 00″ which is about 67 minutes. and so far that seems to have fixed it. I assume if I’m idle for over 67 minutes and then I get an email, it’ll “pop” again, so my choices are to change the IdlePowerState to 00, or increase the PerformanceIdleTime to an even bigger value. You may find many copies of these values in the registry, remember to only change the one under hkey_local_machine system CurrentControlSet.
Good luck. By the way, funny coincidence, I just bought my wife a dv7t, it doesn’t have this problem.
For those reading this anew, the sound is as if someone were plugging the speakers into the jack.
So, basically it says to alter the value in the registry key to set the time-out value to be a lot higher.
I have put the value “2c ff 00 00″ in this key: \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\xxxx\yyyy\PowerSettings\PerformanceIdleTime, which means that in Performance Profile the stand-by mode will only be initiated after a time of 0xff2c seconds of making no sound whatsoever, which means about 18 hours in human language.
In the key \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\xxxx\yyyy\PowerSettings\ConservationIdleTime, I’ve put the value “1e 0f 00 00″, which means 0xf1e seconds (~= about an hour) of required idling before the sound chips kicks into stand-by mode in Power Saving Profile.
(Note: the xxxx and yyyy are GUIDS, large identifier strings chosen by Windows. To find the right one, you need to look up your audio chip in the Device Manager and look at the Properties, tab Details and there Device class guid)
If you looked closely at the default values in your registry, you might have noticed an idle time of 300 seconds, as stated in the quote above. This means that if the audio chip didn’t play a sound for 5 minutes, it’s kicked into stand-by mode, which means that whenever a sound is played from that point onwards, it will start with a *pop*, and that’s annoying.