High latency with Alder Lake CPU

[Kent Y]

My old PC is an AMD Ryzen 1700 with a MOTU M2 USB interface and I was able to get 5.8ms (256 sample) latency without getting late buffers in cakewalk.  No special tuning was done.  See below for full system spec.

I built a new PC using an Intel I5-12500, using the same MOTU M2 interface.  The best latency I can get without late buffers is 46.4ms (2048 sample).  See below for full system spec.

Since the 12500 CPU is faster, I was expecting latency to be similar if not better than the old PC.  I've tried everything I could think of and done a lot of research on the internet but am still unable to answer why the latency is so much worse.  The only thing that made any difference was to edit the registry for the Pro Audio multimedia entry (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Pro Audio)  and set the CPU affinity so that it would only use 2 CPU cores.  That allowed me to bring the latency down to 256 samples without getting late buffers but I don't understand why utilizing fewer CPU cores improves the latency.  I'm also concerned about what other limitations I may run into by using fewer CPU cores.

A strange behaviour on the Intel PC is that after rebooting and loading my project in Cakewalk, I can run at 256 sample latency for the first 20 to 30 seconds without any problem.  After that, the performance indicator shows the engine load increase significantly and the late buffers start occurring regularly and that causes popping sounds.

I'm wondering if anyone has any insight into what could be going on?

 

specs

MOTU M2 USB interface, connected to USB 2 port (using other ports didn't make any difference)

AMD PC Spec: AMD Ryzen 1700 CPU.  Asus Prime B350-Plus MB, 16GB RAM/2133Mhz, GeForce GT 710 2GB GPU, Samsung 960 NVME

Intel PC Spec: Intel I5-12500 CPU, MSI Pro B660-A D4 MB, 32GB RAM, 3200Mhz, GeForce GT 710 2GB GPU, Kingston KC3000 NVME.  The integrated GPU of the 12500 is disabled in BIOS.

Edited April 20, 2022 by Kent Younkin

[Jack Stoner]

I've had latency problems caused by NVIDIA video.  It can be tamed but I haven't found a way.  I only use AMD Video cards for this reason.   

Two DAW users on the Dell forums have reported latency problems with new XPS desktops that come with NVIDIA video cards.  Both reported the latency problems were "fixed" by removing the NVIDIA cards and using the Intel CPU Video.   

 

[Jim Roseberry]

FWIW, You can build a properly working DAW with higher-end Nvidia RTX video cards.

I'm typing this message on a machine running a 12900ks with RTX-3070.

This machine can run Helix Native at 96k using a 32-sample ASIO buffer size (completely glitch-free).

With my Orion Studio Synergy Core (audio interface), that yields 1ms total round-trip latency.

 

DPC Latency comes down to hardware/drivers.

It certainly helps if the motherboard provides advanced settings/options (which can affect DPC Latency).

Many off-the-shelf machines limit BIOS settings that presented to the end-user (to keep novice users from fouling-up their machine).

That's fine for general-purpose use (where ultimate performance isn't necessary), but it's a major disadvantage for a high-performance DAW.

 

If you're building a "12th Gen" machine and you're looking for high-performance, you want to be using a Z-690 chipset.

If you can't get DPC Latency "in-check" with Motherboard tweaks and hardware driver changes, it's time for a new motherboard.

 

 

[Kent Y]

TL;DR

I didn't have the "high performance" power plan selected.

 

LatencyMon mentioned checking power management and by default I had the balanced plan selected.  So I went through the items in the balanced plan but didn't understand the implications of "minimum processor state" which was set at 5% and therefore I hadn't changed it.  After researching it more I realized that the CPU cores were going into low clock frequency mode after 28 seconds (I saw that number mentioned in my BIOS overclocking section) and the CPU load of my project wasn't enough to keep the CPU cores out of low power mode.  That is why things worked when I set the CPU affinity to use a single core.  By using a single core, the load on the single CPU core was high enough to keep that core from entering low power mode.   I found the HWinfo app to be useful for monitoring the CPU clock.

When the CPU is running at a low frequency it takes some time to  ramp up to max frequency and that creates latency in the audio processing.  The high performance power plan sets the "minimum processor state" to 100% so the CPU cores are always running at max frequency.  With just that single change I can now run the same project at 2.9ms/128 sample latency and never exceed 50% on engine load.

[David Baay]

Should have started reading at the bottom. Based on the last paragraph of your opening post, I was going to suggest the issue was exactly what you found - CPU throttling. In addition to setting High Performance in the O/S, you should go into BIOS and disable SpeedStep and C-States if available.