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?

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

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.

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?

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.

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)?

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.

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!

...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!

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 . 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.

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

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)

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).