The Interface is Fireface UC. The computer is Win 10, 6 CPUs, Intel i7 2.5 GHz with 32 Gb RAM. Drivers and system have the latest updates.

I hope some of you will take the time to review the added info I am providing and speculate on possible causes. I’m a musician, not a tech guy (though I am a retired Electrical engineer I have not worked in the field for 20 years, an eon in internet time.) i understand enough about troubleshooting to work it but I don’t know anything about the nitty gritty of audio interfaces.

The problem is ONLY in Cubase. No other applications have any issues. I have another post on this forum concerning the Fireface driver getting corrupted  every 2-3 hours scrambling playback completely. forcing me to close and start up Cubase again. This problem disappears when I switch the driver to Asio4All which lacks a lot of features of the RME driver, but at least I can keep working. I am assuming the noise I am hearing has something to do with  the way my system is configured. I will look into Totalmix and Digicheck, which I am not familiar with. Don’t know how to record in loop back, any suggestions for instructions how to do this? What would that tell me? I’ll check on the Power plan. Any pointers on optimizing for real time audio? I recently ran LatencyMon  and it tells me everything looks good for real Audio despite all the clicks/pops. The problem is on the monitors, 3 sets driven by the Fireface analog outputs. I never use headphones, would it tell me something valuable if the headphone outputs were working properly?

All the projects I am working on are 90% midi, using virtual instruments, mostly from Spitfire, East West and Orange Tree. Does that suggest anything? Is my DAW, Cubase 10 pro, possibly an issue? No indication of that on the Steinberg forum.

Any ideas appreciated.

What is the procedure to optimize my system for audio, it never came up for me. Is the fact that LatencyMon thinks it’s ok meaningful?

The type of user you are, changes the more posts you make. It’s just a term not what you are.
The video card should be ok. I have one of those myself. I was looking for an optimisation document that I’d seen by Zoom but can’t find it. Do a google search for win 10 optimisation for audio. I use Cubase 10.5 and now 11 without problems on windows versions 2004 and 21H1. How many instruments are you loading?

I am using typically 10 virtual instruments per project. Always Superior Drummer 3 (2-3 instances), Orange Tree for guitars and bass (Kontakt based, 2-5 instances) Spitfire BBC symphony (3-5 instances). My system seems to handle it ok, very occasional temporary failures of Cubase to handle playback and display in real time. I’ll check if the problem is there in a project with just a couple of audio tracks.