http://bluemic.com/blog/2013/10/...

• Mic Picks Up Keyboard Reddit

• Using Audition's Automatic Tools. To begin, go to Effects Noise Reduction Automatic Click Remover ( Figure 5, below ). Choosing Audition's Automatic Click Remover As with any edits you make in Adobe Production Premium before rendering or saving a file, these are nondestructive edits, so try the Heavy setting first ( Figure 6, below ).
• But soon after that I finished my mid tower and my case sits closer to the front of my desk. Everyone says they can hear fan noise. I've tried everything I can think of to stop it. I put the mic under my desk, figuring that the sound wouldn't be able to pass through the desk to the mic, but it still seemed to.

Oct 29, 2017 - Background or 'ambient' microphone noise can be a real pain, but there are tricks to help reduce it. To some extent any sound recording will.

Go through the Bluemic page and use it as a checklist, it doesn't say anything I wouldn't repeat here word for word.
One major point about the YETI is that it is a side address mic - you speak into the side, not the top — see the do’s and don’ts image on the page linked above.
If, after checking Bluemic’s own advice for better home recording, the background sound persists, try and see if any of these are causing noise:

1. - The noise is from the PC power supply. Try using a USB hub that has it's own power supply. If you're using a laptop, try running off of battery and the charger and see which one is better.
   
2. - […] Maybe the mic is picking up the hum through the desk […] talking about mechanical vibrations. The fans and hard drives in your PC/laptop could be vibrating the table which is coupling into the mic. Move the mic and see if the noise goes away.
   
3. -The noise is caused by EMI/RFI. Try moving the mic around the room and see if it gets more or less noise when in different positions. Try a longer USB cable so you can move it around more. Once you've identified what is causing the EMI/RFI then you can do something about it.
   
4. - And there is always the possibility that the mic is bad. Try using it on a different computer, in a different building. If you still have problems then get a different mic.
   

[Source]
How can I get rid of the annoying background hum on a new Yeti Microphone (top voted answer by David Kessner - edited for context/clarity by me)
Further tips from the Twitch forum on Reddit.
1. Shock Mount
2. Mic stand or clamp or something similar
3. Pop filter
4. Control the gain
5. Cardioid Pattern
1. A shock mount will help with vibrations etc. so say you knock the table or mic stand etc.

Mic Picks Up Keyboard Reddit

2. Will get the mic off the table reducing clutter and moving the mic further from your fan.
3. Will help drown out surround sounds to a certain extend, it really help if your near loud noises :P.
4. Turn the gain down, if your mic is near your mouth then their should be no need to turn the gain up.
5. Cardioid will make Sound be picked up mostly from the front, but to a lesser extent the sides as well.
[Source] (Edited for clarity by me.)
Removing microphone noise during live broadcasts • /r/Twitch