Optiplex 7020 Ghost Sound

With you're mic or other line-in device you're using, troubleshoot the wire by the plug-in.  While recording, try things like wiggling the wire or turning the plug back & forth.  The same for the other end of the wire.  Make sure the jacks are clean.

Meanwhile...  Have you tried anything different for recording/recording studio software?  Any other devices?  And...  Any difference between front and rear audio jacks?

What's you're OS, Win10? - In case it also helps others answer.

Are you increasing the volume on your recording?  I don't mean just turning up the speakers, but increasing the volume on the recording itself and re-saving?  If it's overdone, I noticed some things can be ultra-sensitive.

Hopefully not a loose internal wire with the front audio jack.  And hopefully nothing nearby causing electrical interference.

Hello Brad,

Thanks for the reply. I have tried both front and rear line-in jacks. I've also unplugged everything from the line-in jacks with absolutely nothing feeding into the computer and there is still the same noise. The only way to stop the noise is to disable the Mic/Input in sound settings.

It's almost as if there is a mic on the motherboard that is picking up the sounds from the fans. But as I understand it there is no on-board mic on the Optiplex 7020.

I'm almost to the point of reloading the OS (Windows 10) and try again. And by the way, this system is being used to stream our services, so there is a camera feed going in through an HDMI to USB converter and the sound is coming from the sound board. But again, the problem continues even with everything disconnected.

For those that have asked, the 

I purchased this machine five months ago through Amazon, but have since discovered that the warranty on this expired some time back. Amazon offers a 1 year parts and labor, so may end up having to return it.

If there is an internal speaker, typically on top of the HDD cage in an MT, disconnect it.  Don't know if that will work, but I figure it's worth a shot.

Sorry to hear it's been so much trouble.

Please don't post service tag.  That's non-public info that we wouldn't want manipulated.

I unplugged the Int Spkr, but no change.

With absolutely nothing plugged into the Mic/Line-in, I can hear the fan type sound through a headset, or simply through the recording software.