Your new PC is in warranty so have them fix it.
My son has a new laptop which I had to get a new cable since it used that new combo mic and headphone jack rather than the old PC two jack system.
A few months back I started to have a weird problem with my microphone. I hadn't used the mic in about a month, but when I went to use it the people I was talking to on the other end said all they heard was static. So I tried to troubleshoot the problem and after listening in on the mic I found out they were right.
After a week of trying to figure it out I got a new soundcard - that didn't change anything.
After the soundcard upgrade I just decided to get a new pc - I'm still having the exact same problem.
The only thing in common between these two PC's is the position where I put them.
I know the problem isn't the mic because I tried it on multiple different laptops and on a few people's I know PC's. I've also tried different mics on both my PC's and was still experiencing the same static.
I'm pretty desperate at this point and any help would be greatly appreciated.