Practical example with Nvidia issues:
A possible solution to Nvidia DPC latency problems (how I solved my own problems-Nvidia audio and Windows power plans)
As seems to be a fairly common problem, I occasionally got some crackling/clicking and even complete failure with my Focusrite Scarlet Solo. Latencymon attributed the problems to my Nvidia drivers causing DPC latency. I have an Nvidia graphics card and cards need drivers, so it seems I’m just screwed, right?
Wrong!
First, I downloaded an installer of the latest Studio Ready drivers* for my graphics card (just the drivers, not GeForce Experience, which is worthless bloatware). Then I disabled Windows Update and completely disconnected the PC from the Internet. I then used Display Driver Uninstaller (while booting in safe mode; I also removed some of the DDUsettings) to erase all traces of Nvidia drivers…
* Studio Ready drivers are more stable, Gaming Ready drivers may be slightly more performant. I don’t tend to play a lot of advanced games, and even if I do, I’m more of a person for single player and co-op, so fussing about small performance increases is really not something that matters in the least to me.
While rebooting, I looked at my BIOS settings and turned off a lot of random crap; I actually looked at every processor-, memory-, voltage- or frequency-related setting and saw if I needed to turn it off. If I don’t need it, it goes away. It probably means I’ll have to do some fiddling around with virtual machines, but right now I don’t need that, and I’d rather solve my current problems than worry about future other things I might want to do….
Okay, back to Windows. Install those Nvidia drivers, but choose a custom installation and do NOT install the HD audio drivers! (Also, don’t install GeForce Experience, which is worthless bloatware. I say this twice because you have to reject it twice)
After this, disable all audio devices to which your graphics card is connected; if you have monitors with built-in speakers, disable those speakers in Device Manager. Do the same in Windows sound settings if they are still in there. Make sure they are gone.
At this point, I had roughly halved the DPC latency I was getting from the Nvidia drivers, but it was still quite significant…. The next thing I did was what you should always do, but what I only did last because I assumed it was irrelevant (because of course I assumed I had already done it, which I had, and that another program I installed didn’t undo it, which unfortunately it had)…
Switch to High Performance power mode and in your advanced settings set your minimum CPU state to 90% and your maximum to 100%.
Also make sure it doesn’t do any other power-saving things; selective USB suspend? No, that’s not necessary. Connection state power management? No!!! Turn it all off, it just causes hassle. It may be useful if you have a laptop, but on a PC, even with the crisis in the cost of living, these things won’t save you enough money to make up for the hassle.
Finally, where before my DPC latency was always in the red zone in Latencymon, and I was constantly getting crackles, beeps and dropouts, I am now constantly in the green zone, with no problems so far.
If I encounter any more problems, I will update or delete this post.
My problems seem to be caused by two things:
Windows Power Plans – ALWAYS use High Performance, Windows does weird things under the hood just a little differently when you use this mode, which for some reason you can’t apply to other power settings. And the annoying thing is that various programs and drivers add new power plans and set you to them by default, so even if you think you’re on High performance, you may not be!
Nvidia HD Audio Driver – While this did not completely solve the problem, it also had a significant impact and Nvidia users seem to have DPC latency issues across the board, probably because of this… There is clearly something wrong with Nvidia’s HD audio drivers.
Still testing
