Anderton
The backstory: With sample buffers below 256 samples, regardless of the interface I would often get the dreaded audio system motorboating where Sonar would lock up, not be stoppable from the Task Manager, and require a reboot to get working again. Recently, there was a thread here about latencies and I thought I would try using lower latencies again. The problem persisted. I just assumed that the V-Studio drivers were kinda old, that my projects were getting more complex, maybe I needed a faster processor, etc. 
 
Then I thought maybe some  Device Manager process was causing a problem (someone had mentioned improved performance by disabling the network card), so I started experimenting. Of course I had already disabled the Realtek High Definition Audio driver but there was also another audio device under Sound, Video, and Game Controllers called AMD High Definition Audio Device. It didn't have an option to disable, only uninstall, so I never messed with it.
 
The fix: In my computer's Device Manager under System Devices, there's an entry titled High Definition Audio Controller. I was able to disable it, and poof - the AMD High Definition Audio Device disappeared from Sound, Video, and Game Controllers. Since disabling this, Sonar has run flawlessly for two days straight on two different CPU-heavy projects with a 48 sample buffer!
 
A possibly related issue: It's been noted several times in these forums that the choice of graphics boards can have a huge impact on Sonar's performance. Maybe it's not the graphics card itself, but the audio driver installed with a board. I'm pretty sure nVidia boards install some kind of audio driver as well.
 
I am one effing happy camper right now. 48 samples!! If anyone looks into this on their system, please report back and let us know if it helps. I can't believe the difference.
 
 

Hi all,i haven't any other audio device in my system devices.I have only the Focusrite Saffire 26\io listed.
I have a Nvidia graphic card and i have disabled the realtek on board audio card in the bios setting.
If I'm wrong I accept suggestions.
Best

GIM Productions
 
Hi all,i haven't any other audio device in my system devices.I have only the Focusrite Saffire 26\io listed.
I have a Nvidia graphic card and i have disabled the realtek on board audio card in the bios setting.
If I'm wrong I accept suggestions.

 
You may not need these tweaks. If your graphics card hasn't installed weird audio devices, then what I'm suggesting isn't relevant.

Note: After disabling the drivers under System Devices, you need to reboot the computer for the changes to take effect.
 

More research...
 
On my HP laptop at work, which is using the TASCAM US-366 interface, I found two "High Definition Audio Controller" entries. I disabled them, re-booted, and again, there was a significant increase in performance at low latency settings. This might be more universal than I thought.
 

Anderton

Paul P
Thanks for this !
 
I also have the AMD HDA-device.  However, I can disable it, and just did as I don't need it.
I don't have it appearing under System Devices.

 
Interestingly, after the next power off/power on cycle, the driver had re-installed itself. However when it did, this time it included an option to disable. So I disabled it and disabled the one under System Devices. We'll see what happens tomorrow when the computer gets turned on.
 

If you choose Custom Install wtih nVidia drivers you can actually stop the nVidia audio getting installed so you never have to worry about it. Also choose "Clean Installation" which supposedly removes ALL drivers and settings, but in my experience (unless installing to a fresh W instal) one still needs to tweak the registry. 
 
Here is a process for showing those hidden devices (the tab in Control Panel does not show all of them) that still can affect performance, even though "supposedly" not loaded or indeed showing...
 
Windows Device Manager only normally displays Registry entries for devices that are currently connected, even if you use its 'Show hidden devices' function, but if you follow these steps you can force it to display redundant devices that are no longer connected, so that you can delete them once and for all.
First you need to start the Windows Command Line Prompt, by selecting the Run option in the Start menu, entering 'cmd.exe' into the text dialogue and pressing return. This will launch a DOS window into which you type the following commands, pressing return at the end of each:
 
set devmgr_show_nonpresent_devices=1
 
start devmgmt.msc
 
Device Manager will automatically appear after the second command, and now if you go into its View menu and select 'Show hidden devices' you should see quite a few 'greyed out' items referring to missing hardware. For more details on what's safe to delete and what's not, check out www.soundonsound.com/sos/jun04/articles/pcnotes.htm.
Here are some additional points that may help. First, before deleting any greyed-out item belonging to old hardware, if you double-click on it (or right-click on it and select Properties), select the Drivers page and then click on its Driver Details button, Windows may be able to display a list of all the driver files the old hardware used. Since these are not deleted when you delete the Device Manager entry, it's worth noting down the non-Microsoft ones for later removal by hand, if you want to be thorough.
 
 

Thanks! To which I would add...set devmgr_show_nonpresent_devices=1 is essential for finding zombie MIDI ports so you can delete them and get around the Windows MIDI port limit (used to be 10, I think it's 16 or 32 now).
 
FYI Microsoft is investigating the MIDI port limit thing. I've been involved in that dialog, mostly as a nag 

Please be careful about disabling the high definition audio device on the computer since it will surely disable all onboard audio for other apps and could adversely affect apps that rely on it.
I think Craig listed "High Definition Audio Controller" which has a different name from HD audio device..
I don't think you can generalize that any onboard audio device will cause latency problems. Normally onboard audio is a completely different path from an external audio device. So if you are using ASIO it shouldn't be impacted by onboard audio. 

Anderton
More research...
 
On my HP laptop at work, which is using the TASCAM US-366 interface, I found two "High Definition Audio Controller" entries. I disabled them, re-booted, and again, there was a significant increase in performance at low latency settings. This might be more universal than I thought.

 
Are you using ASIO or WDM for your main audio interface? Also is your onboard audio device an NVidia audio device?

Noel Borthwick [Cakewalk]
Please be careful about disabling the high definition audio device on the computer since it will surely disable all onboard audio for other apps and could adversely affect apps that rely on it.
I think Craig listed "High Definition Audio Controller" which has a different name from HD audio device..
I don't think you can generalize that any onboard audio device will cause latency problems. Normally onboard audio is a completely different path from an external audio device. So if you are using ASIO it shouldn't be impacted by onboard audio. 

Actually Noel, it does not I can still use my onboard audio anytime I want. And if one has the Audio interface as the default (and unlocks the Exclusive mode) then ALL apps using the system default are using that device anyway..............nVidia "High Def" drivers have been an issue for a LONG time...and why they also STILL affect the available 10 midi slots in W is also a mystery.

Anderton
Thanks! To which I would add...set devmgr_show_nonpresent_devices=1 is essential for finding zombie MIDI ports so you can delete them and get around the Windows MIDI port limit (used to be 10, I think it's 16 or 32 now).
 
FYI Microsoft is investigating the MIDI port limit thing. I've been involved in that dialog, mostly as a nag 

I'm pretty sure it's still ten in Windows 7 at least, I looked into it when it came up for me. Some reports claim that the limit has been fixed in Windows 7 but I know for a fact that's not the case. For anyone who doesn't enjoy registry diving, you can install the Korg midi driver, it comes with a utility to remove old and phantom drivers.
EDIT: glad to hear at least some dialog is going on there