I've been trying to put together a 486 retro PC and so far no major issues, the only thing remaining is the sound card. I have a couple of Sound Blaster Pro 2 CT1600 cards so I thought about using one of those in the build, especially considering that the SBPro2 was my first sound card back then.

So, I installed one of the cards as well as the setup disks from vogonsdrivers.com. Everything went well, but as soon as the test utility initialized the card, there was this annoying high pitched noise, like some sort of interference or an old dial-up modem trying to connect. However, when playing the test sounds for FM and digital, the noise goes away and it sounds great.

I then tried playing some Doom and other games and they also sound great, but as soon as I go back to the command line, the noise starts again. The strange thing is, when playing a game or even in Windows 3.1, it works as it should: sound/FM are good and when there are no sounds or music playing the card is pretty much silent. But exiting to DOS causes the noise to start again, and I have to either lower the volume or turn of the speakers.

I tried the other CT1600 as well as several sets of speakers (old and new) and the same thing happens. What do you guys think could be causing this noise? As I said, I had an SBPro2 back then, and I don't remember having this problem (it was a CT2600 though).