07-08-2009 06:29 AM - edited 07-08-2009 08:20 AM
Since I got my SL500, it's been plagued by audio problems - skips, pops, crackles, and even slurred stutters that sound like something being played under water. As of today, after a few hours of testing, I can safely say that I've found the causes for _all_ of the problems, at least on my machine, and I'd like to share what I've found for other people having the same problems, because the available info on this issue is incredibly lacking.
I've got the SL500 with a P7370 and GeForce 9300M GS. Running a fresh install of XP Pro SP3 32-bit.
1. The first of the problems, namely the skipping and popping (half-second pauses, seemingly random clicks, stuff like that), was caused by the nVidia GeForce 9300M GS driver. This driver includes a power-saving mode for laptops, known as "Powermizer". Every time the driver switches from power-saving mode to performance mode (the clock jumps instantly from ~170MHz to 750 or so), it produces a huge DPC latency which causes the sound card to hang and produce an audible pause or click.
In the nVidia Control Panel, the description states that it is only used during battery operation - this is _wrong_. The utility clocks down the graphics when they're not in use, during battery AND mains operation. Turning off the Powermizer gets rid of the skipping and popping completely.
Here's a screenshot of the DPC Latency Checker and GPU-Z running together. The red spikes in the Latency Checker _always_ coincide with the clock jumps in GPU-Z (strangely enough, it only spikes when switching _up_ in clock speed - not down).
As a side note, the IBM Power Manager utility (not the driver) also causes very high DPC Latency spikes (in the red on the DPC Latency Checker, but not off the chart like the nVidia driver) whenever the Fn+F3 hotkey is used or the mouse is moved over the battery icon on the taskbar.
2. The second problem only showed up when the system resumed from hibernate or standby - it does not occur if the system has not been hibernated or put in standby.
-After waking from standby, Windows start sounds (after swiping your finger through the fingerprint scanner, it'll give a little beep to say the print's been accepted, for instance) often sound slurred, sort of in slow motion and sounding like the sound is being played under water.
-Music often sounds slurred for the first two or three seconds of the song in Winamp, then goes back to normal.
-Sometimes a few seconds in the middle of a song will slur, then go back to normal. It's also happened that it didn't go back to normal until I hit standby and resumed again.
The cause: Once again, faulty power management. Deactivating the three power saving options in the POWER section of the BIOS (Intel C-State tech, and the two PCI Express power saving options) completely solved the problem. I can now go to standby/hibernate and resume as often as I want, and don't have a single problem with slurring audio.
Now, my SL plays music just fine, and I should have no problems running DAW programs on it, but it runs very hot.
Before my tweaks, the CPU ran around 30C, and the graphics card at around 50-55C. Now the idle temperatures are 40C and 65C, respectively. This is tolerable in mains operation, but when running on the battery, it lowers the battery life by about 50%... not good. For people who need the battery life (which wasn't great to begin with ), this really sucks.
But hey... at least I can listen to music without wanting to throw the laptop out the window every 5 seconds now. Hope this helps for other people with SL-series audio problems...
-edit- After about 10 consecutive hibernate/standby and resume test runs, problem #2 is back. Guess I jumped the gun on that one a little. DPC Latency problem is still solved - at least so far.
07-15-2009 04:07 PM
I've been having the same problem on my Lenovo T400 -- the sound slurs or disappears completely, often after waking from Standby. I've been able to fix the problem a few times by unplugging the power cord, but when the laptop is in the docking station unplugging it brings on a Blue Screen of Death. I just fixed it by changing power schemes in the Power Manager. I had read another report blaming the Power Manager, but upgrading to the latest version didn't help.
I don't want to employ your #2 fix (which sounds like it didn't fix the problem anyway). The manual fix via Power Manager is a pain but tolerable until Lenovo fixed the $@#! software.
07-16-2009 12:07 AM
Do you have the DPC Latency Checker? I find that running it in the background after a resume from hibernate/standby stops the slurs.