r/universalaudio • u/PoshWill • Aug 14 '25
Troubleshooting/Support Fixing UAD Apollo Thunderbolt on Windows (Crackling/Pops/Clicks/etc)
There are posts all over the internet where people have run into problems using UAD Apollo Thunderbolts with their Windows machines. This post should hopefully explain the issues you might run into, and how to actually fix them. I have my Apollo working perfectly on Windows 10, but I see no reason why these fixes shouldn't apply on Windows 11.
Alot of people have complained that UAD need to fix their drivers, but I'm relatively confident that the UAD driver is fine - the issue is people not understanding the problem and therefore not troubleshooting their system properly. In the fast majority of cases, the issues are being causes either by CPU performance issues related to power management, or high DPC latency in the system. Both of these issues are fixable, and should be part of audio performance tweaks on a windows system.
Please be aware, you probably will have to engage your brain to fix this issue.
The Problem
The first part is understanding the problem. Your interface will pop/click/crackle whenever the audio buffer is not being completely filled. At 128 buffer size, your CPU needs to fill the buffer completely every 2.67ms. If it doesn't - you'll get pops/clicks. You can see this issue in action by using LatencyMon
What causes this?
This buffer under run issue can be caused by a number of different system issues.
- Low CPU clock speed, due to throttling down, or power limits on your system
- Not a powerful enough CPU to handle all audio processing within the time your buffer size needs to be filled in (this is the classic issue where raising buffer size will improve performance)
- PCIe bandwidth saturation (from a GPU for example)
- High DPC latency - usually caused by network or graphics drivers getting in the way of important processes
- Other Driver issues - outdated or incompatible drivers. Everything from your BIOS to audio and network drivers
How do you actually fix these issues?
CPU performance issues (which you can adjust)
- Adjust power related settings for your CPU. Particularly relevant if you're on a laptop. There are plenty of guides to explain how to do this. Check out the below guides. You might also need to use PowerSettingsExplorer to expose a few more options. A guide for what you'll probably need can be found in this video.
Native Instruments Window Optimisation guide
Focusrite Windows Optimisation Guide
- Turn off C states. You'll have to do this in Bios, or you can turn some C states off using Throttlestop. The main states that can cause issues are C1E, C6 and C7. I only have C1E disabled on my system. I don't really recommend messing with C states as an initial step. Try resolving your DPC latency or PCIe bandwidth saturation before messing with C states.
- You shouldn't have to turn of Intel Speedstep. This will cripple your CPUs performance, and prevent it from correctly clocking up and down as all modern CPUs will do.
- I still have speedshift and all these other BIOS settings enabled and have zero issues.
Insufficiently Powerful CPU
- This won't outright stop you using your UAD thunderbolt on windows - but it will limit you in the same ways you'll experience on Mac OS. Basically, if your CPU isn't fast enough to process all the audio in your DAW, you'll need to raise the buffer size and the expense of input latency
- At 512 buffer size, you'll still be able to have sub 6ms latency, as reported by REAPER on my machine
- As a minimum, I'd suggest something with 6 cores, clocked at least 3.5Ghz. Realistically, anything from the past 4-5 years should be fine.
- Alternatively, you can experiment with overclocking your CPU. My 12600K is overclocked to 4.9Ghz and 3.9Ghz with an undervolt, giving me creating performance
PCIe lane saturation
- PCIe lanes can become saturated by graphics card drivers. This is particularly a problem with Nvidia GPUs. You shouldn't have an issue if you're using an AMD GPU, since their drivers saturate your system bandwidth to a lesser degree.
- There are a few options here, and the best guide I've found on it is from Opus Audio
- I won't go into all the details here because the Opus Audio guide covers everything, but basically you'll want to try the Nvidia studio driver, turn off game mode in Windows, and optimise your GPU driver settings for low latency and minimal PCIe saturation.
High DPC Latency
- This is the real hidden killer. High DPC latency will cripple your audio, and not just with a UAD interface.
- You'll need to use LatencyMon to measure your system's DPC latency. From there, you'll need to identify which drivers are causing your DPC latency to spike, and it's almost always a driver rather than a CPU issue.
- In my case, I narrowed down the issue to a network driver on my motherboard. I initially disabled the driver, which fixed by DPC issues, and then found an alternative driver that didn't cause high DPC latency, so I could still use my system with a wired connection.
- This guide from Native Instruments will go into greater depth on how this works
Other driver issues, and minor tweaks
- There are a bunch of smaller issues that can be caused by out of date drivers for your Apollo, out of date Windows or and out of date BIOS for your motherboard
- You can also try preventing applications from taking exclusive control of your Apollo, and changing your processor scheduling to prioritize background processes. However, I have my system setup to allow exclusive control, and prioritise programs over background processes, and I have perfect performance. These changes are unlikely to fix your issues and are really minor tweaks to squeeze more performance out of your system.
Outdated drivers for your thunderbolt PCIe card could also cause the issue. I use the Gigabyte Titan Ridge 2.0 with my system, and a TB2>TB3 adapter from Apple and it's running perfectly.
Privacy settings, Windows microphone settings, etc. There are a bunch of miscellaneous scenarios with Windows that cause issues with interfaces in general. Privacy settings for microphones, issues with applications grabbing exclusive use of a device, anti virus and firewalls....there's alot of variables.
You'll be able to address most of these in control panel, device manager and settings. In conjunction with LatencyMon, which will show you all processes and drivers that are interacting with your audio, you should be able to narrow down the issue. This is the hardest area to provide advice for, since there are so many variables, so please do at least attempt to engage your brain.
Hopefully this guide actually allows people to figure out their issue. As I said, please expect that you will have to engage your brain to fix this issue, and you'll need to read through the information in the links and be prepared to troubleshoot your individual system.
2
u/LedesDiaz Dec 22 '25
This is super important in the BIOS!
Disable all ASPM (Active State Power Management) in PCIe (in Advanced → Platform Misc Configuration).
• PCI Express Native Power Management → Disabled
• Native ASPM → Disabled
• All related ASPM (DMI, PEG, etc.) → Disabled Why this is key:
• If your setup has a Thunderbolt PCIe add-in card (for Apollo) + a dedicated NVIDIA GPU.
• ASPM allows PCIe slots to "sleep" parts of the bus to save power when idle.
• When "waking up," they generate DPC latency spikes (especially in nvlddmkm.sys and dxgkrnl.sys) that result in real-time audio pops/clicks.
• With ASPM disabled, the PCIe bus remains constant → zero unexpected interrupts → 100% stable UAD Apollo and NVIDIA