Max CPU spikes

Hi All.

I’m sorry to bother everyone with another CPU question, but hoping someone can help.

I noticed for the first time that I’m getting alot more audio dropouts due to CPU spikes.

Using Rack standalone, with no modules except an audio2, the Average CPU is hovering around 1.3%, but the max CPU is dancing all over the place, sometimes spiking at 200%. These values are different to what the task manager measures.

I’m almost certain that this has nothing to do with Rack, but rather some other process causing issues. So what I’m actually asking is:

Do the CPU meters in rack measure the entire PCs CPU usage, or only that which is used by Rack?

Hopefully I can iron this problem out and get back to making music.

Thank you all for your time.

1 Like


I noticed I had the exact same issue yesterday. 60~70% CPU load on an empty patch with no module at all. And VCV says it uses 3% of the GPU (which is true, it only uses every CPU ressource available).

So I opened my biggest patch and thought “what if VCV doesn’t use 6 threads” ? I told VCV to use only 2 threads. The patch was still playing with no crackling or artifact, with 15fps instead of 30~40, the task manager said I was using 30% CPU and the rest of Windows became faster and usable when I’m on VCV, which was not the case, VCV was slowing down the whole system.

So I guess it just uses all the computing power you have on default.

As for VCV meter, since it uses the GPU, I think the meter is for the GPU only. I didn’t verify if I had the same values on the task manager’s meters but I think they match since it’s GPU.

I think VCV should integrate CPU metering, since it uses that much power just for opening itself.

1 Like

Thank you, that clarifies things regarding VCVs meters. I have a feeling that it’s my Nvidia drivers causing problems. Could have been a Windows update or something. I’ve never had these problems before yesterday. Usually Rack is very stable.

1 Like

Yeah, I mean it’s hungry but stable. I never looked at the meters before so I couldn’t say if it’s new but it feels like it’s new, at least on an empty patch. I’m used to slow and hot when I have a 5-6 row rack, which is normal and expected.

I’m on Nvidia too, I’ll update just in case but GPU usage looks usual so I doubt it’s the case

I found out I was completely mistaken. I don’t know why I thought VCV was using GPU computing power. I read something a few years back about audio software that runs on GPU, and I might have confused.

Answer from Squinky

From Andrew

VCV’s metering is CPU, tho it’s not displaying the exact same values as the task manager, the values are not that far from it.

Thanks for the help @nnnegazul . So do you think that the CPU meters in Rack only measure what Rack is using? And not the entire PC? I’m just trying to find the root cause of the sudden CPU spikes. If it’s not Rack, which I don’t think it is, it must be something else. But it’s affecting Rack. I will have to run some tests.

1 Like

I believe spikes are due to VCV only. It’s not worst than any DAW, sometimes I have 200% peaks in Ableton too, could be bad buffer, could be bad VST interlacing, could be anything and I’m no dev.

After looking at VCV and Windows for a while, they are absolutely never displaying the same thing.

But I think there is a simple reason : I believe Windows is displaying the amount of power Rack uses, and VCV displays how much of the CPU power it is allowed is used by modules.

Again, for spikes, it could be anything. Tho the only extreme spikes case I have is when I use Nysthi Simpliciter and its variations, making them unfit for recording music, too much audio stutters over a whole song (had 2 or 3 in 5 minutes, which is not a lot but it still breaks immersion).

Keep me posted on these tests by DM if you find something

1 Like

This might be something relevant to this discussion, if using Windows:


Thank you so much @marc_boule . That is exactly what I was looking for. Although I am running on ultimate performance. This article explains alot. I’ll have to check what is throttling the CPU when I get home. At least now I know it has nothing to do with Rack.


well, it COULD be a bad module. I don’t think @marc_boule is saying it’s impossible, just that it’s not your first suspect maybe.

The meters in rack are supposed to only show rack, btw, so if there is “other stuff” running on your computers eating CPU it should not show up in the rack meters.

1 Like

Hi Squinky. That’s interesting because if I have an empty patch, with only an Audio2 module in it, it’s still spiking. The avg CPU is stable at about 1.3%. But the max CPU is jumping around. This only happened yesterday for the first time. Before that everything worked great. Which is why I think its a Windows update or something which is messing with the CPU. But if you say that Racks meters show only what Rack is doing, then I’m even more confused. Unless it’s the ASIO drivers which are causing it.

Did you reduce the number of threads ?


Very interesting, thank you. I’m already running VCV in performance mode but I didn’t know about the hidden ultimate performance mode. So if my toaster dies in flames today, it’s on you :stuck_out_tongue:

1 Like

Yes. I always work with one thread until I need to up it. I don’t usually need more than one thread.

1 Like

For me the issues are while using Voicemeeter. When using my usual ASIO device I have no stuttering/crackling, but using Voicemeeter with a big patch and OBS to record it, it is impossible.

But last year I recorded a video while using Voicemeeter with Resolume displaying 60fps visuals on another layer and I didn’t have this issue, so either it’s since V2, either it’s the same issue than you, and I couldn’t say.

Thank you to everyone for their extremely valuable contributions. After updating all drivers and rebooting the laptop. Rack is back to Normal :grinning:. There was a process in the task manager called “system” which was responsible for the CPU spikes. It was going nuts, and so when it used all available CPU, there was nothing left for the audio to work. Obviously an update of some kind. So everyone should take Andrews advice and DISABLE UPDATES!!!. But it does seem as though background processes affects the max CPU in RACK. Not the avg though. Back to Racking!

1 Like

are you sure of what you are saying ? on my POOR notebook m1, I get 3% max… no spike…

1 Like

I am sure I had stutters when I used Simpliciter.

However, I am not saying Simpliciter is directly involved, I should have been more precise. I have to reset my computer for a while now, and my CPU is known for not handling throttling very well. I have to undervolt it and dig into what I find about the subject but I’m picky about BIOS manipulation, since I don’t want to burn my toaster with a bad input.

Also, every time I used it, it was on top of my patch, I never used it on its own yet.

That said, after monitoring the situation, the spikes were coming from Simpliciter. I have to see if I can reproduce the situation, it was also before I know I could reduce threads used by VCV and thus, CPU power it uses.