If it is a buzz that goes away when you touch the metal chasis, then that's a grounding issue. Try these steps.
Important: check to see if you are using balanced or unbalanced cables. Could be the main culprit.
-Make sure your interface can used balanced cables.....If so majority of the time this will fix your issue.
If not continue.....
1.Make sure all of your audio equipment is plugged in the same outlet. ( Power conditioner is always a great option, but not necessary)
If they are all in the same outlet......Try moving one of the monitor plugs to another outlet.
If that doesn't work.....Try running an extension cord from a different outlet to see if that side of the house has a grounding issue.
Next check to see if your audio cables are on top of your power cables.....if so separate them.
This is very important to note.....
Does the humming stop when the xlr is unplugged from your monitors? If yes read (A)
If no.....read (B)
(A) IT'S a ground loop issue, and this should help you.
https://www.amazon.com/dp/B00BARTW42/ref=cm_sw_r_apan_i_P8N1GVV6XRPVF8T80SR5
(B) If you are here, that means the buzzing (50-60hz tone)continues with no xlrs plugged into your monitors, which means there is toroidle hum....or transformer hum.... and you will need a slightly more expensive but proven fix.( Less than having an electrician come out)
iFi SilentPower | DC Blocker - Blocks Any DC Offset, IEC Connector https://www.amazon.com/dp/B08XWHJRZ1/ref=cm_sw_r_apan_i_X86VYK8E0DWTY4YXCQCF
Hopefully this helps
This info relates to a 50-60hz buzz/hum
Side note: If its computer noise, thats something different. If you can hear the computer working through your speakers...like if you move the mouse and can hear the sound change, or there is static in the speakers...thats usb ground loop, and requires a different device.
iFi iDefender+ USB Audio Ground Loop Eliminator (Type A > A) https://www.amazon.com/dp/B0849J33T9/ref=cm_sw_r_apan_i_9KN8R470WQ8V5FDZQ9ZY?_encoding=UTF8&psc=1
Make sure you know exactly what you are hearing.....static or buzz.....Then you can select the correct device(s) for the job.
Hopefully this helps.