Buzzing noise with new headphones.

Plug the headphone into the rear GREEN speaker jack and see if you still get the noise. If its OK there, there is something wrong either with the front panel assembly in the case or possibly the wiring or how its routed to the HD Audio connection on the motherboard.

you might have 2 devices hooked up to that channel port it happens when you have aftermarket sound card or some sort of hardware

I would get the MB manual and check all connections from the case to your board if not resolved it might be a bad chip for your sound device that fused to the board

Got access to a stereo or another machine zeta if the buzzing isn't there using them then there is a problem with your audio set up mate.

As matter of curiosity what frequency range is this new set compared to your old ones?

The other thing would be to know what sort of drivers the headphones are using voice coil or piezo?

No buzzing using any stereos or anything.

Frequency range is 10Hz-22kHz, 40mm neodymium driver and it's piezo.

EDIT: Old headphones had a frequency of 14-20Hz

Disconnect the front panel headphone jack connector from the motherboard. It could be causing feedback.

Also, do you get the noise with regular PC speakers plugged in?

If the speakers buzz without being connected, I wonder if there is an AC power line problem that is causing all the "buzzing"? Is the AC receptacle that you are plugged into properly grounded? (and properly phased)? Any way to move the PC to a different AC Power line feed (and phase)?

I am thinking along with fireberd that maybe you may have a "ground loop" within the machine.

I know from the past with old stereo systems for example if one had a power circuit where you plugged in one device and because he ground was connected to the chassis and it in turn was connected to ground at the input / output socket that a second device that was similarly grounded via it's supply it caused a loop via the connecting leads - any extraneous hum from the ac supply would be picked up by the loop that was created. I used to cure this by disconnecting the ground to either the output or input of one device so interrupting the loop, there were other ways of course.

But this was purely a mains frequency hum - 50Hz and I don't know what frequency you are experiencing via the phones. But similar situation might exist though it is hard to imagine.

Even simpler would be to try a different brand of phones, and get your money back for the ones you have now, at least that is what I would do.