Buzzing Microphone wont stop unless i touch the case

[givemeyourcake]

I've been banging my head against the wall for the past 4 hours trying to get my microphone not too buzz, i've tried almost everything I can think about i've tried reinstalling the motherboard i've tried disconnecting all the fans disconnecting the graphics card switching power supply switching cables for the power supply try going through a USB connection tightening the screws disconnecting all other USBs, i'm running out of things to do and no matter what I do the bus won't stop unless I touch the case clearly this is a grounding issue but I don't have an outlet with a third prong what can I do to fix this issue because I am open for all kinds of suggestions literally i've looked at all posts all forums 50 different websites they all explain in different ways but nothing has worked

 

[givemeyourcake]

Right now I have to use my anti static wristband connected to my power supply in order for me to use my microphone