Intel WifiLink 4965 AGN Driver's DPC Latencies causing audio glitches in Windows 7 X64 (RTM)

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After many tests I can ensure that the wireles adapter Intel WifiLink 4965 AGN is causing high DPC Latencies with an interval of 10 micro-seconds in Windows 7 64 bit (Release to Manufacturer). I have tried the latest drivers for Windows Vista 64 bit (12.4.3.9) and Microsoft's drivers included in Windows 7 with the same results: high DPC Latencies with an interval of 10 micro-seconds and eventual very high DPC Latencies causing audio glitches with a length of up to one second. Is there any specific driver for Windows 7 64 bit (Release to Manufacturer) that solves this issue?? Will there be??

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Yoshiblade, When the wireless driver/adapter is active, are you passing any traffic (download/upload/internet browsing) or is the adapter connected and idle only?

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Make/Model Laptop: Lenovo t61p

Product: 4965AGN

OS: Windows 7 Professional x64

Driver Version: 13.2.1.5 (5/31/2010)

Problem: High DPC spikes constantly, causing audio problems.

Tests done: Disabled Wireless driver - DPC spikes almost completely go away and audio is normal, re-enabled and DPC spikes come back and audio glitches again.

Adapter disabled: http://imgur.com/6V07x.png http://imgur.com/ECkHN.jpg

Adapter enabled: http://imgur.com/iSrcZ.png http://imgur.com/1DWve.jpg (it tends to get worse over time)

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What is the state of the wifi when the spikes happen? are you connected to AP? If yes, are doing download/upload/internet?

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Yes, I am connected to AP and download/upload is happening. When I am not connected, but the wifi is turned on, the spikes are minimal, similar to when I turn off wifi.

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What happens if you disconnect from the AP but keep the WiFi on. Do the audio glitches still happen? Can you try it and confirm please?

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I did try it and like I said, the spikes are there but nowhere near as bad as when I am connected. Also, the same spikes are there even when I turn wifi off completely, so I don't think they are related to the wifi. I don't see the point of trying to solve what's causing those spikes though, when the wifi is making it 100 times worse.

The audio glitches happen pretty much anytime there is a spike.

[idata]

Thanks for the update. I was trying get a better understanding of the behavior in order to help solving it. The question remains, if you are connected but not doing any download/upload/internet, besides the spikes, do you still hear audio glitches? Or does the audio glitch happen only when doing donwnload/upload/internet (traffic)?

[idata]

Yes, the audio glitches even when there is minimal or no traffic, as long as it's connected to an AP. As long as there are spikes, there are problems with the audio.

[idata]

Hi everyone,

I have this problem also: high latency peak every 10 second caused by the driver Intel Wifi Link 4965 AGN.

More digging with Microsoft Windows Performance Toolkit (xperf) showed that the high latency (2 ms) of this driver is caused by the function ndisMTimerObjectDpc and ndisInterruptDpc of the module ndis.sys.

Make/Model Laptop: Asus V1S

Product: 4965AGN

OS: Windows 7 Ultimate x32

Driver Version: 13.2.1.5 (5/31/2010)

Problem: High DPC spikes (>2 ms) every 10 s, causing audio problems.

Tests done: Disabled Wireless driver - DPC spikes almost completely go away and audio is normal, re-enabled and DPC spikes come back and audio glitches again. Older drivers were tested and it did not solve the problem.

Please, help!

[idata]

...in addition to the post just above...

Below is some more details on this driver problem (as measured with DPC Latency Checker v120 http://www.thesycon.de/eng/latency_check.shtml and xperf http://msdn.microsoft.com/en-us/performance/cc825801.aspx).

-Intel WifiLink 4965 AGN Driver causes on my system peak latencies of at least 2 ms. The average latency is around 5 ms.

-Without using the connection, the peaks occurs precisely every 10 s. The wireless card can be turned on/off it does not affect this phenomenom.

-Using the connection continuously (e.g., media streaming, downloading over wireless connection), the frequency of latency peaks increases a lot and they occur erratically.

-Latency spikes affect dramatically the audio and media streaming capability of the computer by adding lags and crackling noises.

-As already mentionned above, this latency is caused by the function ndisMTimerObjectDpc and ndisInterruptDpc of the module ndis.sys.

-The latency peaks disappear completely when the driver is disabled in the Device Manager of windows.

-A google search of this problem ("WifiLink 4965 AGN Driver latency DPC" or "ndis.sys latency dpc") shows that this exact problem affects a LOT of people. They all report the same symptoms as mentionned above.

Could the developers of the next driver built address this problem?

Please! 

[idata]

Make/Model Laptop:

Asus F3E

Product:

3945 ABG

OS:

Windows 7 Professional x86

Driver Version:

13.2.1.5 (7/2/2010), plus some previous version (also by Intel), plus Microsoft's wlan driver shipped with the OS (12.4.1.4 - 3/26/2009)

Problem:

High DPC spikes every 10 seconds resulting in glitchy audio (buffer underruns) and other IO glitches

Tests done:

Disabled Wireless driver - DPC spikes go away and audio is normal, re-enabled and DPC spikes come back and audio glitches again.

It seems like the situation becomes unbearable more rapidly when high traffic-generating applications (e.g. emule) have been running for a while. Then I get almost continuously red spikes (i.e. every second or so), that are much higher also, being in the 8000-16000 range.

Closing the application at that point doesn't restore the situation: the frequency of the spikes goes back to 10s^1, but audio glitches are still there, as to say: once the problem pops out, the only way to get normal audio reproduction is to disable and re-enable the wlan adapter.

DPC tool, wlan adapter enabled: http://www.imagesticky.com/viewer.php?file=q4t3pna2ok1o6f6j3cc2.png

after disabling wlan adapter from the Device Manager: http://www.imagesticky.com/viewer.php?file=ganoqawpkdtfnpbvl.png

(forgot to reset the maxim value, so it still says 5172...)Someone here: http://forum.notebookreview.com/dell-xps-studio-xps/252552-m1530-m1330-sound-stutters-post-your-dpc-latency-here.html http://forum.notebookreview.com/dell-xps-studio-xps/252552-m1530-m1330-sound-stutters-post-your-dpc-latency-here.htmlsuggested to disable the 802.11a standard in the device configurations. Needless to say, it doesn't fix the problem for me.

PS: I used to use this same notebook with XP Pro SP2 (32Bit) and I wasn't having this issue.

Please Intel give us a fix soon

PPS: here it goes, after some hours with emule open:

http://www.imagesticky.com/images/ze88mg3tnhv6jg9od0wt.png

[idata]

Hello, I have the same problem - 4000us spikes every 10 seconds. This is causing my external USB sound card to stutter occasionally (setting ASIO buffer to 2000-4000ms doesn't help).

I have a Sony Vaio SZ780N5 (Santa Rosa) laptop with Intel 4965 AGN.

OS: Windows 7 Ultimate with latest Wi-Fi driver from Intel website (13.2.1.5).

[idata]

Hello,

I have been trying to find a solution for my bad ping (mostly noticable when playing online games, e.g. Battlefield: Bad Company 2)

My first thoughts included: interference, problems at the ISP and other stuff that could cause latency problems.

With some more tests (moving my wireless router into close range etc.), I still had problems. So started a second test on a secondary notebook.

I pinged the same IP adres on both machines (both via WLAN) and came to the conclusion that it was the machine that was causing the problems, because the secondary machine didn't have strange latency.

So with the help of the internet I ended here

My machine: Acer Aspire 6935G-844G32BN

Product: Intel® WiFi Link 5100

OS: Windows 7 Professional x64

Driver version: 13.2.1.5

Problem: Just like others, every 10-15 seconds a latency spike causing bad lag during online games

Tests done: Cross referenced the ping results between 2 laptops, one with Intel Wifi Link 5100, one without. Same location, same IP adres.

I hope a solution can be found

[idata]

Yeah, Seismic, I think that your problem does not related to ours, but I could be mistaken. We are experiencing audio glitches and not spike lags. Please post some screens with DPC Latency Checker running.

[idata]

If I'm correct the opening post states that he/she has:

Fjtorsol wrote:

high DPC Latencies with an interval of 10 micro-seconds and eventual very high DPC Latencies causing audio glitches with a length of up to one second

I too have high DPC latencies but it results in something entirely different, so although my problem doesn't sync with the thread name, whats causing it is completely the same.

Here are the screenshots you asked for:

This one is with wireless: http://imgur.com/ygTDW http://imgur.com/ygTDW

This one is with lan (wireless disabled): http://imgur.com/RQsu9 http://imgur.com/RQsu9

Using lan when wireless is enabled is causing latency aswell.

Hope this explains why I replied in this thread

[idata]

I noticed within the last couple of weeks that this issue developed on my system. I have Windows 7 32-bit installed on an HP dv2000t, which actually has the Intel Pro/Wireless 3945abg wireless adapter. I experienced the same behavior with skipping audio and increased kernel & system CPU usage, which led me to the DPC latency utility. Disabling the wireless adapter would remedy my issues completely. Updating and rolling back drivers made no difference, and even installing a new usb network adapter (Airlink101) did not make a difference. I got to thinking that the only thing I had changed to the system was windows security updates. I checked through the updates in the last couple weeks and sure enough I found this related update was installed - http://www.microsoft.com/technet/security/Bulletin/MS10-048.mspx http://www.microsoft.com/technet/security/Bulletin/MS10-048.mspx . It's an update to the way windows handles kernel mode drivers, which apparently caused the source of my issues. After uninstalling the update (KB2160329) per the instructions on the linked page, I have had no more issues with audio skipping and the DPC latencies have gone down to normal levels. I hope this helps you guys out. I know I've been pretty frustrated with this for the past couple weeks. Check out your windows update history, right around the 8/12/2010 time period.

[idata]

Thanks for sharing this info, but in my case it can't be the cause of the problem because I keep Windows Updates turned off.

In fact, the one indicated by you is listed among the available updates (8/10/2010, btw).

So it's not the cause of the issue for me

Thanks anyway

[idata]

I have uninstall KB2160329 and nothing changed. The peaks of high DPC latency (2-5 ms) induced by Intel WifiLink 4965 AGN Driver are still showing up every 10 s.

Thank you for the suggestion though.

Make/Model Laptop: Asus V1S

Product: 4965 AGN

OS: Windows 7 Ultimate x32

Driver Version: 13.2.1.5 (5/31/2010)

[idata]

Well it seems that the problem hasn't gone away. It appeared to for a couple days but it may have been due to rebooting or something. I am out of ideas.

[idata]

Hello everyone,

I had no time for tests so far, but I just recognized, that there is a new driver available on intel homepage. Its dated to the 10. of September 2010 and has got version 13.3.0.137. As I did not find a changelog it seems to me that we will have to test if this new version fixes our problems.

Kind Regards

KinTutt

[idata]

I still have the same issue with 4000 us spikes every 10 seconds even with the new driver.

So it doesn't help, unfortunately...