Wasn't there a post in here that linked to a program that could identify which driver was bogging down the CPU? I'll have to do a search on that.
Still, though, most of the drivers on here are ones right from the Dell driver download page or from XP's own database. The only one I can think of right off that isn't is the video driver. That came from AMD's site.
I went ahead and ordered a sound card for the computer, BTW. When it arrives, I'll see what happens. In the meantime, I've switched a bunch of XP services to manual and even disabled a few. Many of them were automatic. It has helped a lot with the audio problems, but there are still a few when the computer is in my truck.
OK, I found a DPC latency checker and followed the instructions. It is pointing to the Dell 1490 WLAN card as the offending driver. That's a Broadcom model. Both this Inspiron 1501 and the Vostro 1000 use the same model of WLAN, thus I installed the exact same driver. The other two laptops have different kinds of WLAN cards--one's a 2Wire nd the other, I think, is an Intel.
I might just switch to whatever kind of WLAN card my wife's D620 has. She says it never has any problems.
OK, I think I have it nailed down ... kinda. I updated the conexant modem driver and downgraded the 1490 WLAN card's driver. I still cannot seem to find a driver for the WLAN card that doesn't cause spikes in the DPC latency, however, I've got it to where the spikes are less often with the WiFi light on, and almost non existent with it turned off. I don't mind so much turning off the Wifi when I'm running the music. The spikes are between 2000 and 8000 nanooseconds, whereas they were off the chart above 16,000 nanoseconds.
The audio is a lot clearer now coming through headphones. I'm at home, which is where the sound seems to be the best.
I still can't wait to get the sound blaster, though. 🙂 If the sound is this good now, the Sound Blaster ought to have exceptional sound to it, just as I've come to expect.
Update: I have obtained a slew of wifi cards. The Intel 3945 cards I obtained are not whitelisted under the Inspiron 1501's BIOS. I have an Atheros AR5BXB6 card installed and I'm running DPC Latency checker.
The Broadcom / Dell 1490 wifi card didn't push the DPC latency at home very much, but it's impossible to shut that card completely down without physically removing it (the card's firmware keeps it searching for a wireless signal even if the drivers are disabled--this works on a hardware level).
So I have an Atheros AR5BXB6 card installed and the latency is terrible. The card came from a Thinkpad. Evidently its firmware identifies it as an Atheros card, which is whitelisted in the Inspiron's BIOS. With the wireless switch off, though, the Atheros card doesn't produce the latency spikes the Broadcom one does. I get more skips with it turned on than with the Broadcom, but it may not skip or stutter at all when it's turned off. The intel 3945 cards produce a flat curve when turned on or off in my wife's Latitude D620.
The biggest problem, though, is that the Sigma Tel audio is simply a codec, and as such, it lacks an IRQ that a hardware sound chip would have. That IRQ could be assigned to take precedence over the wifi card. Most Sound Blasters use IRQ 5, 9, or 11. I've yet to receive the sound blaster or obtain the latest drivers for the Atheros card.
Bear in mind, though, that with wifi disabled, so far the computer's sound is smooth as glass even using the Sigma Tel audio codec. Perhaps I Can get a better driver for it and eliminate the DPC latency altogether, or I can hack my 1501's BIOS to whitelist the Intel cards. If I can do that, the hacked BIOS will be flashed into the 1501 and into the Vostro with no trouble.
The biggest problem, though, is that the Sigma Tel audio is simply a codec, and as such, it lacks an IRQ that a hardware sound chip would have.
The Sigmatel codec is a hardware chip. On the system board of a computer "codec" means that it is built onto the motherboard as opposed to being built onto a card that plugs into the motherboard. It is mainly the ADC and DAC. In a computer with HD audio, the codec is engineered according to the specifications as defined by Intel, which currently means the High Definition protocol.
In my old laptop,Sigmatel has an IRQ (7).
This should not be confused with software "codec" libraries that interpret between different formats.
Mine lacks an IRQ. Of course it still needs a little bit of hardware to work. The difference here, though, is a simple set of digital to analog converters versus having a full blown audio (slave) processor.
I got the Creative sound card in today. It's a little more sensitive to DPC latency than the SigmaTel thing, but aside from that it absolutely blows the Sigma Tel device away for audio quality. I'm sure if I were to connect via ethernet and disable the wifi, I'd have impressive sound out of this machine with the Creative card installed.
In any case, I've found that the biggest problem is the wifi card causing excessive DPC latency.
I've got several solutions to the audio stuttering problem:
1. Disable the wifi card's drivers through device manager. This can be done by simply right clicking the wireless icon in the system tray and selecting "disable".
2. Install a different wifi card that doesn't have buggy drivers (easier said than done). This may require re writing the system BIOS to whitelist that wifi card, or flashing the card's firmware.
3. Switch operating systems.
Is there a way to assign an IRQ to the sound? If I could assign it a lower IRQ than the wireless, then theoretically the wifi card should experience the dropouts before the audio device does.
Wait a sec... I found I was running the laptop in the maximum power saving mode. Once I opened it up to maximum performance, the Creative card's skips and pops have all but vanished. It skips a bit with the wifi card on, but both devices (as expected) perform better with the CPU turned up to max. I'll see how it does on the road. I also made a TON of adjustments to the wifi settings. I Googled one of the advanced settings for the dell 1490 wifi card and a list of almost all of them and what they do showed up. The list is on the main Dell site.