XPS 8960, chasing DPC latency gremlins

Question

I bought one of these machines during black Friday/cyber Monday sales and I'm just now getting around to trying to set things up. I'm intending to use it to replace a 5-year-old Inspiron that I've been using for general computing and audio recording/MIDI/DAW work in Reaper, using a 3rd gen Focusrite Scarlett 8i6 USB interface.

I started getting the intermittent dropouts and crackling audio and ran LatencyMon to see what was up. I talked to a basic support rep briefly, but they were little help and referred me to pay extra for "software support."

LatencyMon seemed to identify the Nvidia drivers (I've got the model with a 4060 ti) as the immediate culprit, so I ran through the litany of suggestions that come up for the issue on this board and all over the web:

wipe and reinstall Windows 11 via Support assist OS recovery (haven't tried the clean non-Dell reinstall as yet but I have recovery USB drive ready to go)
Run ddu to uninstall Nvidia driver in safe mode, then NVCleanstall to pull down only necessary components for Nvidia driver
enable high performance power plan
disable USB selective suspend
set min/max CPU to 100%
set Nvidia device to MSI mode
set processor affinity so that GPU and audio & interface use separate processor cores
disable Atom cores/e-Cores in BIOS
disable onboard audio and Nvidia audio
disable all Dell and Killer services

While the first few tweaks seem to have tamed the Nvidia driver's DPC latency, I'm still getting random spikes within 10 minutes or so. Primarily seems to be from storport.sys, with the system sitting on an open browser tab doing nothing else, Focusrite box not even plugged in.

I think I'm still in the return window for this PC but from what I'm seeing this isn't necessarily a Dell issue or limited to this model, seems an ongoing thing with the current gen Intel processors and Windows 11. I'm not at this computer currently so I don't have logs or LatencyMon screenshots to post for now - is there anything I'm missing? Does it make sense to keep chasing the issue on this PC or would I be chasing it regardless of manufacturer/model?

RoHe · Answer

Have you read this about fixing storport.sys latency?

One of the things suggested is switching BIOS from RAID (standard Dell setting) to AHCI. Don't just change that BIOS setting or PC may be unbootable.

There is an easy way to make that change without losing data, but always good to back up the boot drive (NVME SSD) first...

Open Cmd Prompt window, Run as administrator.
Copy-paste this command, which will start Windows in Safe Mode the next time you reboot: bcdedit /set {current} safeboot minimal and press Enter
Restart the computer and tap F2 to enter BIOS setup.
Change the SATA operation mode from RAID to AHCI.
Save the change and exit Setup. Windows will automatically boot in Safe Mode.
Open Cmd again, as in step #1.
Copy-paste this command, which will start Windows in Normal Mode the next time you reboot: bcdedit /deletevalue {current} safeboot and press Enter.
Reboot and Windows will automatically start with AHCI drivers enabled.

Test latency again...

anthomic · Answer

Thanks! I just tried this out, and storport.sys is definitely acting better. Something is still causing latency spikes after a few minutes basically sitting idle with Edge open and not actively loading anything. BIOS is up to date - that's one thing the support tech was able to verify.

EDIT: Apparently I either forgot to completely disable the Killer services or something in the safe mode/AHCI switch toggled them back on. Testing latency again now with Killer services stopped and disabled. I let it run for a while then came back to this:

RoHe · Answer

What happens if Edge isn't running at all?

Is the Killer control panel loading at boot, even with those Killer services disabled? If you have any xTend services listed in services.msc disable them too (part of Killer).

You could disable Waves MaxxAudio and see if that helps...

Lots of posts on this forum and around the net about ntoskrnl.exe and wdf01000.sys causing audio latency so google for them...

FWIW, there's a thread about another XPS 8960 with audio latency issues, and that user gave up and returned the PC...

anthomic · Answer

Weirdly, the SupportAssist OS reinstall didn't install the Killer panel or MaxxAudio, so thankfully I'm not contending with either. I did try disabling core parking today. I've seen far fewer massive spikes since then, during a few different 20-30 minute sessions streaming either Spotify or Youtube with no audible glitches (even as LatencyMon reports over 1ms).

I'll definitely seek out more info on wdf01000.sys, as that seems to be the holdout. Thanks for the guidance!

anthomic · Answer

Weirdly, the Killer software and MaxxAudio didn't get loaded along with the SupportAssist OS restore, so at least I'm not contending with those.

Earlier today I tried disabling core parking and that seems to have brought things down considerably (highest measured interrupt being around 1ms). I was able to stream audio via Spotify as well as Youtube videos for at least 20-30 minutes straight this afternoon. The only time I heard any audible glitch was when I had media player streaming some music and attempted to download a couple things at once, then suddenly tcpip.sys caused a massive DPC spike (which isn't surprising when I think about it).

Currently installing Reaper and a few choice VSTs to see what performance is like, but it seems these tweaks may be helping.

RoHe · Answer

Did you respond to my last post? I got Notification in last few min from the forum saying you posted again, but I don't see any post(s) after my last one...

anthomic · Answer

@RoHe​ Yeah, the forum was acting weird for me last night. For some reason my replies weren't showing up after I submitted them (thus the semi-duplicate posts). This morning I've been streaming audio from the PC while keeping tabs on LatencyMon. Playback has been solid for hours - seemingly no glitches, even with 1.2ms highest reported DPC execution time. I also loaded up Reaper last night and played back a project with several audio tracks fine, even tested realtime MIDI playback with a VST instrument. I'm still keeping an eye on it, but I think it may be at a useable point now...

RoHe · Answer

@anthomic - You apparently posted something "inappropriate" in the post I couldn't see. So it and all your subsequent posts were put on moderation (hidden) until moderators had a chance to remove whatever naughty thing you said. Please follow the forum's code of conduct to avoid being moderated. (FYI: Repeat offenses could get you banned permanently!) Thank you...

Glad the system seems to be behaving better. You may also want to fully disable (or uninstall) both SupportAssist and Dell Update, both of which are known to cause latency...

lawdin · Answer

It’s likely a broader issue with Intel + Windows 11, not just Dell. Since you've tried nearly everything, returning it might make sense—unless you're willing to keep tweaking or try a clean non-Dell Windows install first.

lawdin · Answer

Could someone please provide me official nvcleanstall link?

lawdin · Answer

@lawdin​ Thanks guys I got the link

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XPS 8960, chasing DPC latency gremlins

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