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Precision 7740: still acpi.sys latency issues render it unsuitable for audio production?
I just purchased a Precision 7740... on paper a wonderful machine for portable music production. I've so far installed Windows 10 pro, some driver updates, and pulled the whole thing up to the latest windows update (including the latest KB4505903).
The problem is LatencyMon. This tool is a good indication of whether or not you can get clean, low-latency audio. I am unfortunately seeing reported latencies of 2000 - 4000 microseconds regularly. According to LatencyMon, these are mostly related to ACPI.sys. And these numbers are generally too large for glitch-free audio at reasonable pro audio buffer sizes.
These are, depressingly, far worse results than I have on my 10-year-old m6400.
I have spent days now trying out all the potential fixes I can find online, at manufacturers "tune your laptop for audio" sites, etc. At one time or other I've tried turning off almost everything in the bios, particularly battery and power-saving related settings, cpu-throttling, etc.
At one time, according to an xps thread here:
https://www.dell.com/community/XPS/XPS-15-9570-DPC-latency-ACPI-SYS/td-p/6113042
It appears that Frank Azor, and then later Nelson Mak were working on this. It is not clear whether or not it was actually fixed for the xps or not.
I would like to find out if there is an imminent fix for this before I have to consider that this machine, which is 100% used for audio production, will need to be returned to Dell.
Some info:
- Precision 7740
- i9-9980hk
- SATA mode set to ahci in bios
- USB powershare disabled in bios
- C-states and Speedstep turned off in bios
- Speedshift power management turned off in bios
And a whole host of "never sleep", "never turn off display", "high performance" etc settings in a custom power plan based on the "high performance" one.
Any experiences with this on the new-model precisions? I'd like this one to work out if possible.
Thanks...
samos1111
489 Posts
0
August 5th, 2019 01:00
Reports for the 7590 are mixed, some say it is passable (though not exactly good, just like the 9570 fix), some having issues.
Also check this about a Windows issue https://www.gearslutz.com/board/music-computers/1266677-huge-latency-issues-latest-1903-windows-release-solved-10.html
Have you tried turning off wifi (Killer?) and the NVidia GPU? Both drivers are reputed to be no good for real-time.
Hope752
3 Posts
0
August 5th, 2019 18:00
Attached is a link where a guy goes into latency on the 7740- just google translate it to english.
Hope752
3 Posts
0
August 5th, 2019 18:00
glittle.sd
4 Posts
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August 6th, 2019 13:00
Thanks. Interesting. Although I'm not clear what his conclusion is regarding dpc latency? I may be missing something, but he sees approximately 2ms readings and just kind of moves on? Is he saying those are okay for him? Or "this needs to be looked into later"?
In the mean time, I did try turning off wifi, but it didn't seem to help much. So I went back to the beginning and reinstalled a generic Windows 10 pro and am working my way through that again. Without network on, and without any drivers installed yet, and without Windows Update running, things do look better in LatencyMon, but not amazing. My ACPI.sys DPC latencies for the moment are keeping to around 1000 microseconds, sometimes up to 1300.
I have done BIOS config (turn off speedstep, c-states, etc) and the usual config settings (optimize power for performance, everything always on when plugged in, favor background tasks, etc).
Once I install the wireless driver and connect to a network, then a lot changes fast because of the updates and so on.
I'm not sure if 1300 ms is acceptable yet or not... the intent was for this to be a VST performance machine running with the smallest buffers (lowest audio latency) possible.
glittle.sd
4 Posts
0
August 7th, 2019 11:00
Quick update... I confirmed that my acpi.sys latency spikes were mostly staying at about 1000 - 1300 ms with that basic install and no network.
Installed wifi drivers, enabled wifi, but not yet connected to network, the numbers stayed about the same.
Connected to network, and driver updates and MS Store installs started happening. After that all settled, my DPC latency peaks for acpi.sys approximately doubled, and became more frequent.
I had turned off "automatic driver updates", but for some reason, got a bunch of them anyway.
Went ahead and ran windows update and allowed KB4505903 (the latest update to 1903) to install.
No improvement.
Also, UserBench reports the CPU is in the bottom 3% of all i9-9980hk, and that both its speed and turbo speed are "240mhz". That might be a typo, since it is 2.4ghz, but what bothers me is no turbo boost. I checked, it is enabled in the bios. Not sure if any of this is related to the DPC Latency trouble above. If not, I'd like to keep this thread about the latency issues and will deal with the cpu readings later.
dwikkel
3 Posts
0
April 4th, 2020 02:00
MarcoWhites
1 Message
0
April 8th, 2020 13:00
I have the same problems with my Precision 7520. Unfortunately I understood (too late) that Dell laptops are especially bad for music production.
As you I've spent a lot of money to be able to work on the go with the best performances. This is so irritating, since for me it's been a big economical sacrifice.
Anyway, I was able to lower the DPC latency stopping all Dell services in the Windows Services tool as indicated here:
https://answers.microsoft.com/en-us/windows/forum/all/high-dpc-latency-from-acpisys-causing-audio-clicks/a7977dd5-6a52-4ee7-91bd-83180c21c1c2?page=1&rtAction=1582813247907&tm=1582813532816
Also this website is well done:
https://www.bluecataudio.com/Blog/tip-of-the-day/how-to-optimize-a-windows-laptop-for-low-latency-real-time-audio/
Unfortunately though I think the best solution would be to sell the laptop and never buy a Dell again if you want to work with music.
Let me know if you find any solution