Not sure if this is the right place to ask this, but here goes:
Background: I recently bought a new synth keyboard to use with my computer to record music. As part of this setup, I bought a USB audio interface (Presonus Audiobox USB 96), two Yamaha HS5 active studio monitor speakers and the requisite cables: two 1/4" (instrument) to XLR cables and the USB connector that came with the USB interface.
I set it all up and everything was sounding great...until I fired up a game (Overwatch), at which point both speakers started emitting a low-medium frequency buzz at a low, but clearly audible, level. I tested with other games and had the same issue, but playing Spotify or watching YouTube videos was fine - no noise at all.
I tried various things to see if it would resolve the problem (I can elaborate if necessary), but on a hunch that it might be GPU-related (since it only happens when gaming and this would be the most GPU intensive work), I opened Task Manager and observed the GPU usage when loading the game. Sure enough, as soon as the game finishes loading, the GPU hits > 80% and the noise appears. To try and prove this was related, I dialled down the game resolution, and sure enough when the GPU drops, both the frequency and the volume of the noise decreases. With a more demanding game (Assassin's Creed), the GPU hits 99% and the frequency is noticeably higher and louder.
If I run a game in windowed mode and minimize it, the GPU usage drops to 0% and the noise will disappear with it.
So... how on earth do I fix this? My GPU is a relatively new GeForce RTX 2070 and the motherboard is new also (MSI Z390 GAMING PLUS). I have tried every USB connector on my chassis, including USB3 and USB2. I also tried plugging the audio interface into my computer keyboard's USB port to see if it would help, but the noise seems identical.
I'm really desperate to solve this, as I basically can't play games now unless I use headphones and turn the speakers off, which kinda defeats the point of having them.
If it helps, the XLR cables are these: https://www.pmtonline.co.uk/stagg-nac3psxmr-3m-balanced-male-xlr-to-stereo-6-3mm-jack-cable. They're 'balanced' cables, which I was told would improve the sound by reducing noise, so hopefully, they aren't the problem!
UPDATE: I'm still having this issue. I have now tried purchasing a UPS (to ensure a clean power supply to all components: PC, monitor and speakers). I also tried buying a new USB cable between the PC and audio interface, one that has ferrite coils on it to supposedly reduce noise.
With my GPU removed and using on-board HDMI output, the noise vanishes, but obviously gaming is impossible as the built-in graphics are nowhere near capable. With either my old GTX970 or RTX2070, the noise is the same and very distracting.
I can only assume this is a motherboard issue, but have no idea how to verify this? I don't want to spend out on a new board only to have the same issue. My current board is an MSI Z390 Gaming Plus.