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

Hello,

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

Symptoms:

- 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.