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XPS 15-9570, Windows 10, high DPC latency, acpi.sys


I have a dell XPS 15 9570, and I have big issues with on board and external audio.

HW Spec:

Dell XPS 15 9570, i7 8750H, 4K screen, 16g ram /512g ssd, qualcomm Killer wifi and then intel AC-9260, nVidia 1050 Ti with latest WHQL drivers, bios v1.2.2, all drivers to date as of 2018/15/07


- audio cracks and pops with system audio when watching videos, listening to mp3/flac, playing games with built-in card,

- audio cracks and pops with  external ASIO soundcard (focusrite scarlett 18i8 2nd gen) when running pro DAW software with 256 samples buffer @48Khz or 512 buffer @96Khz

This can damage external speakers and makes the machine unusable for live audio or even standard multimedia use.

What I did:

- applied all tweaks recommended by my external audio card's manufacturer https://support.focusrite.com/hc/en-gb/articles/207355205-Optimising-your-PC-for-Audio-on-Windows-10

- ran LatencyMon and found that TCPIP.sys and ndis.sys were causing 4ms DPC latency spikes, followed by ACPI.sys 2ms and dxgkrnl.sys 1.7 ms

- swapped  the qualcom card for an intel AC-9260 which eliminated totally the TCPIP.sys and ndis.sys spikes

- now ACPI.sys and dxgkrnl.sys are still causing 2ms DPC latency spikes

- audio glitches are still present

- disabled all peripherals except for keyboard, integrated graphics, trackpad, screen and storage (I disabled wifi, bluetooth, webcam, nvidia graphics, fingerprint reader, ACPI battery manager, cardreader, fall accelerometer, screen touch, etc.)

- disabled Speed-Step/ SpeedShift and Turbo-Boost, disabled virtualisation support in the BIOS to try to minimize randomness in the behaviour

- disabled fastboot

- ACPI.sys latency is still culminating at 1.7ms and causing audio dropouts with either built-in or external USB asio interface

- I've opened a support ticket over at dell with my premium support, the ticket was automatically closed a week later without anyone getting in touch with me.


I've run out of options and am looking for help.


Replies (114)

Adhoc fixes.


- Turn off speedstep, I didn't bother with the other steps

Disable the Thunderbolt 'Auto-switch' option and change to BIOS 


On your Desktop

- install Process Lasso

- Using Process Lasso install bitsum power mode

- Go into power plans and enable (if you cannot see the "change plan settings" look here https://appuals.com/how-to-restore-missing-power-plan-options-on-windows-10/ and apply

- Make sure you are running Bitsum Power mode


If using Cubase or whatever DAW, open up process lasso, ACPI.sys problem seems to occur on CPU cores 0 and/or 1. Just use CPU affinity and remove the DAW from that CPU core, now select "Induce Performance Mode" (something like that). I bought Process Lasso it is that good.


Reboot and you will have no crackles. Let me know if it works for you as I am running UAD too and this has worked and been working for 3-4 months. I under-volted too, changed my wifi to the INTEL AC-9260 (you don't need to do this, I just did) and my machine has made me realise I will never return to Apple :) 

Dell will fix this. I think eventually it will happen. It's hard to provoke and with so many different setups etc it must be a nightmare. When I use this machine just as is it takes a very long time for the crackling to occur, so you could go a long time and not even know DPC Latency existed.




I have tried Process Lasso. While this is a temporary fix, it´s not the solution for our problem. We need Dell to fix it within the OS. First, because we´re letting 2 of 4 cores being unused. If Dell sent back to us half the money we paid these for, that´s OK, if not, I don´t want to rely on that solution. And I have seen ACPI.sys going all over the Cores, when I isolate one, it goes to another...


We have been without an update on this issue for a looongg time now. I would love for Dell to give us an update on the progress of this fix.


My issue concerns a 14 second sound interruption during songs #1 and #2. Not 15 seconds, not 13 seconds, always 14. Strange. I am also a DJ and after hours (days) of exploring and reading latency issue posts, I came to at least two of the partial solutions identified above:
1. Disable WiFi during the show, which visibly and obviously lessens latency using LatencyMon
2. Play through 2-3 songs just prior to show start, avoiding any double-click on the first song and just using e reverse arrow to start the show
3. Disabling the NDIS.SYS driver, and any others not critical

Now what caused me to spend $2000 on a laptop that I purchased specifically to use as a DJ. Good question.  As I explored latency on Dell laptops, I realized there are literally 1000s of owners out there whose computer use is closely tied to audio functionality.

I don't know which is worse, the actual problem, or your total disregard of and lack of concern for your customers. The ACPI.SYS file has been identified as one culprit, and here is is 4 years later. I have a couple of friend/DJs who wanted to go computer-based DJing instead of using CDs. I told them about this issue, so there are two sales that walked out the door on you. And I will take every opportunity to discourage any and everyone from purchasing your products. I also intend to write an article for PC Magazine. Your product is a piece of trash. Having to disable WiFi during a show when I want to access band info, etc. is absurd, though I am forced to do it.


I was going to buy an Xps15 laptop this month to work in my music production. Lots of people told me about that latency problem.... I already had two Dell and always had real pleasure to work with. But now for me, there will be a before and after XPS15.... sorry Dell, I already found another beloved laptop!

Honestly, I haven't had the issue since I applied those adhocs, for me personally, and a bunch of other testers cores 0,1 sometimes 2 (often not) were used.

There's a BIOS update on the Dell support site. They'll fix it man. It's a big company  right? They know the XPS is a Macbook killer (with this fix) - I used Apple for a decade - Dell will fix it completely. Also, it's a little bit of Microsoft fault too, ACPI.sys is a MS driver.

Someone messed up writing the drivers and it's hard to provoke, if you (as a developer) can't reproduce a problem you can't fix it. I'm chilled about it, I know they're going to fix this 100%. Nothing but a bit of buggy software.

Heck you could be told you've 4 mths to live tomorrow, right? The XPS and your 2000 won't be much of an issue then. Just trying to bring perspective my man. Relax, help them, if you can that is. I definitely understand your frustration and I know the feeling. I just think "ah well", life is too short to be getting cranky over silly things. Excuse the "lecture" haha. But those adhoc's should be 100% until it is confirmed there's a 100% fix.

Help mate, help if you like the laptop or just return it. It's not end of the world is what I'm trying to say. :) 


New bios 1.10.1 allegedly improves DPC latency https://twitter.com/AzorFrank/status/1123196191368523777


OOOK dt1.jpgdt2.jpg


Let´s hear from XPS Users if that solves it.


Meanwhile, Inspiron 7572, and many other models, suffering with the same issue, no idea if there will be a BIOS correction for thise as well


On further testing with high performance mode enabled and speed step disabled in the Bios, LatencyMon is all in the green and all under 1ms. Tried various Daws, Reaper, Live10 and Presonus Sudio 4, it is much better for me, no crackling or artifacts. Acpi.sys is about 600us whereas before, it was about 2.9 to 3.0 Ms! This is great news and fair shout to Dell for having a go at this. However, because of this issue and others which still remain and Dells denial of other issues, there is no way that i will ever purchase anything by Dell again.


Latest bios update for g7 series Dell did nothing for latency issues. It's actually worse now. Will there be plans to fix other models as well? Should have stuck with MSI I guess, my old Apache laptop had zero issues with latency...

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