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DPC Latency (Audio Blips)Follow

#1 Dec 15 2012 at 8:44 PM Rating: Good
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So, one of my brand new computers is having this annoying problem. Whenever I'm playing WoW, I'll keep hearing these annoying little blips in the background, and after several hours of googling, I've identified the problem.

I used a program called LatencyMon ( as suggested on some forums, and these two drivers are causing the problem:

ndis.sys (1400ms)
nvlddmkm.sys (700ms)

And the program that causes the most page faults is Microsoft's very own Antimalware service.

I've double and triple checked that I have the latest mobo drivers, audio drivers, and video drivers installed on the computer and the problem still persists. I've tried other solutions like disabling mic/line-in/anything else unnecessary, I've downgraded the audio output to AC'97 instead of the HD Audio to no avail.

I've tried turning off Windows Firewall temporarily and also tried temporarily disabling MSE, no progress.

While running another DPC Latency monitor, I get 150-250ms and every 5th or so tick, it spikes up to 1500ms.

Here's the hardware in that computer:

Mobo: ASUS M5A97 LE R2.0
CPU: AMD Phenom II x4 965 Deneb 3.4GHz
GPU: ASUS ENGT440/DI/1GD5 GeForce GT 440 1GB 128-bit

Most websites that mention nvlddmkm.sys talk about PowerMizer, but that's a laptop power monitor and I'm using a desktop so I don't even _have_ PowerMizer, and most websites that talk about ndis.sys talk about disabling security services, but some of those people say that the fix is only temporary.

The only software I have installed that has anything at all to do hardware monitoring, etc, is Realtek's HD Audio (I've tried uninstalling it, didn't fix it) and nVidia's video driver software.

Anybody on here know anything more about this?
#2 Dec 15 2012 at 10:23 PM Rating: Excellent
29,913 posts
Those two drivers (ndis.sys and nvlddmkm.sys) are your nvidia video card drivers. Check your power options and ensure that "high performance" is checked (Balanced is the default) Alsi try uniunstalling the nvidia driver entirely then reinstall the latest one from It could theoretically be an IRQ conflict, but those are almost non existant under windows 7 or vista for that matter. It might also be a corrupted audio driver installation, even if it is the latest version. try uninstalling it and then reinstalling with the latest build.
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#3 Dec 15 2012 at 11:06 PM Rating: Good
3,440 posts
I thought ndis.sys was a network driver? *blinks*

Anyways, update:

I disabled Cool n Quiet in the UEFI Bios, that got rid of half of the latency issues. I am still seeing spikes every 5 seconds, but these are ~500us instead of ~1500us.

When I disable the Realtek GBE Controller, the spikes stop completely, but leaves me without network (since I'm disabling my network card). Did more googling, peeps with this problem have tried installing other network cards with no success. Blaaah.

I already tried setting power management options, I've re-installed the audio drivers a minimum of 3 times by now.

Family member was playing a fairly loud game, so tomorrow morning I'm going to test it with the room being quiet and see if the <500us latency solves the sound blips or at least reduces them to an almost nonexistent state. You'd think with about a third of the latency it was, it should have made some improvements.

Thanks for the suggestions! I'll try disabling the video card drivers too to see if the spikes keep happening tomorrow morning maybe if the sound blips are still there even at 500us.
#4 Dec 16 2012 at 8:27 AM Rating: Excellent
3,440 posts

It turns out that both ASUS and Microsoft suck at keeping drivers up to date.

Despite me checking several times in WindowsUpdate and also ASUS's webpage (since my motherboard was made by them), it turns out Realtek's website had a newer driver for my network card.

Installed that, and the spikes are gone.

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