Machine: Lenovo T61 Thinkpad
OS: Windows 7 Pro x86
Device: 4965 AGN
Driver Installed: 18.104.22.168
High latency spikes measured with device enabled.
No problem with device disabled.
I am looking forward to seeing an updated driver so I can use my laptop with wireless. Any news?
Tools for measuring DPC latencies:
Thanks for the 2010-11-16 update from Ilenek at Intel (below), but since this problem has not been solved in over a year, I am beginning to conclude that it can’t be solved (or the engineers have more pressing problems). I use my computer for live music production and my only option is to disable the 4955AGN in Device Manager to avoid audio artifacts due to spikes of DPC latencies of well over 2000 microseconds every 10 seconds or so.
Here are my system specs:
Wireless = Intel WiFi Link 4955AGN
Driver = Intel; Dated 10/7/2010; Version 22.214.171.124
Laptop = Lenovo T61p Intel Core 2 Duo 2.4 GHz
OS = Win 7 64 bit
Memory = 4 GB
It sounds like the problem has been fixed in the newer Intel WiFi products (5000 and 6000 series adapters). I’ll check with Lenovo to see if I can upgrade my T61p to one of the newer adapters. Otherwise, it looks like I may have to wait until I upgrade the entire computer before I can use audio with the WiFi on.
Nov 16, 2010
Re: Intel WifiLink 4965 AGN Driver's DPC Latencies causing audio glitches in Windows 7 X64 (RTM)
Just wanted to give you all an update on this issue.
Intel engineering is continuing to research and root cause the problem. There is a fix in 126.96.36.199 and later for the 5000 and 6000 series adapters. The information you have provided has been very helpful. Please continue to test with the newest drivers and report your results on this Forum. I will post a notification here when we have a fix for the Intel® PRO/Wireless 3945ABG Network Connection and Intel® Wireless WiFi Link 4965AGN adapters.
Intel Customer Support
In follow up to my last post (as a guest – post #79 in this thread), I just ordered one of the newer Intel PCIe cards for my Lenovo T61p laptop (Intel® Centrino® Ultimate-N 6300 (633ANHMW); $35.24 at Amazon). It looks like the 5300 series and below are now listed as “legacy” hardware by Intel and therefore they are probably a low priority for the engineers to update the drivers for new OS’s (like Windows 7 64). As Ilenek from Intel Customer Support points out, the drivers with the new adapters have solved the DPC latency issue. At this point, I think that 35 bucks is worth it rather than waiting (perhaps in vain) that the Intel will ever release a driver fix for the - now legacy - 4965AGN. I’ll post again after I test the 633ANHMW to see if the new drivers fix the problem on my machine.
I solved my problem with Latency caused by wifi card.
Through way of elimination it appears that issue is made by Malwarebyte's Anti-Malware.
By msconfig I disabled its service and deleted from startup.
No audio glitching for me!
I hope it will help for you too.
The location of the card varies by manufacturer. In my case, the card slot is under the keyboard; which means I’ll have to take the keyboard off to get to it. If you are interested, check your machines website for a hardware maintenance manual (NOT the User’s Manual) that tells you how to access the card slot. For instance, for my Lenovo T61p, the manual is located her:
It is more involved than, say, changing memory modules, but not super difficult. But before your order a newer WiFi adapter, you may want to wait until I get mine installed to see if the 188.8.131.52 or later drivers fix the DPC latency under Win 7 64.
Hmmmm…..As far as I know, excessively high DPC latency is caused by hardware driver problems (not applications). Did you get a trace to see if the DPC latency actually changed, or are you just listening for a reduction in artifacts? If your DPC latency is unchanged, the Malwarebyte's Anti-Malware may be interfering with the audio stream by a different mechanism.
UPDATE: Unfortunately, after installing the new, 633ANHMW, card, I received this error at boot: ""Error 1802 Unauthorized network card is plugged in, Power off and remove the mini PCI network card."
This could either be due to the fact that I ordered the short ("half-mini") version of the mini PCIe card, or Lenovo needs to do a BIOS update to accept these new cards in their machines. Intel only makes the 6000 series cards in the newer, half-mini PCIe form factor.
I'm going to order the full-length version of one of Intel's newer mini PCI wireless cards (5300 Ultimate N Wi-Fi Link) and if I still have problems, I'll contact Lenovo to see what the problem is upgrading the wireless cards in their laptops. Our Intel contributor to this thread (Ilene) indicated that the current drivers for the 5000 and 6000 series fixed the DPC latency problems. We'll see.
I'll post again after I install the 5300 card.
Unfortunately, you cannot upgrade your card to a 5300 or a 6xxx series adapter because IBM/Lenovo "lock" their BIOSes and will not allow the machine to boot up if it recognizes a foreign card. So in order to stay stock, the 4965AGN is the last supported Wireless-N card that can be used for the T61/p line.
However, you can install a modified BIOS that allows for this to happen by whitelisting all mini-pci cards by going to forum.thinkpads.com and checking under the appropriate thread. Only then you will be able to install the 5300 or 6300 (although, you will need a bracket/adapter for this model in order to make it into a full height mini-pci card since that is the new form factor (half-height)).
My setup is exactly this, a modified BIOS and a Intel 6300AGN card with the bracket/adapter in order to fit the card in completely. The DPC latency issue has dissappeared, except for when I power off the lid while music is playing using FN+F3 and move the mouse or keyboard to turn it back on, music skips and the DCP Latency Checker SPIKES completely, stutterring the music for about 3 seconds then resumes. This never happened with the 4965AGN card. This holds true even after a complete reformat and reinstall and I am using the 6300AGN adapter direct from IBM/Lenovo. INTEL, PLEASE LOOK INTO THIS ISSUE FOR THE 6300AGN ADAPTER!!
Hope this helps everyone else!
"except for when I power off the lid while music is playing using FN+F3 and move the mouse or keyboard to turn it back on, music skips and the DCP Latency Checker SPIKES completely, stutterring the music for about 3 seconds then resumes. This never happened with the 4965AGN card."
In my case on T61 with 4965AGN I have not only audio stuttering but a system stuttering in such situation! So at the same time: high DPC latency spikes, audio stuttering and mouse cursor stuttering as well... System just chokes itself. So it doesn't look like caused by WiFi adapter.