noise from usb audiophile after changing case/power supply

[supernova777]

hey guys
so check this out
i changed my case.. and my psu
and im really perplexed how im getting the same type of noise when moving the mouse cursor
that one would usually associate with pci card audio interfaces..
i thought that the m-audio audiophile would be immune to this type of problem being that its a usb interface
this didnt happen before.. its just started happening now.. could it be a grounding issue with my psu?
the device isnt powered by usb its got its own power connection..
very strange

yes this isnt about a mac its about my pc but im asking for some help here given that im always talking here;)
so please excuse... that this is about my pc

whats funny is before i had this same pc using an old psu from a powermac g3/4 and this problem didnt exist!!

[supernova777]

i had a similar problem trying to use my built in audio with my mdd for pro tools free

trying to find some info
http://www.soundonsound.com/sos/nov04/articles/computerproblems.htm

this article claims the following about firewire interfaces:

Firewire audio interfaces featuring unbalanced I/O can suffer from ground-loop problems, since they are first earthed via the Firewire cable, and then again via the audio cables.

not sure if this is also applicable to usb? could it be creating a loop via the power connection + the actual usb cable?

[supernova777]

http://www.native-instruments.com/en/support/knowledge-base/show/250/how-to-resolve-ground-loop-issues-humming-and-buzzing-sounds/

Shared Power Outlet

Always connect your devices to the same power outlet (e.g. with a multi-outlet power strip). Note that even if the power supply of your laptop computer is not connected, your setup may still be vulnerable to ground noise from an external device with its own power supply. All devices that are physically connected to each other should share the same power outlet. You may also have to separate polarized plugs (two-prong) from grounded plugs (three prong), by connecting them to separate circuits.

[supernova777]

OK I FIXED THE PROBLEM  dead silent now

for the benefit of other people having the same problem lets analyze what was causing my problem

i have a powered speaker that has a bal/unbal 1/4" input jack
i forgot i had a Y splitter in this jack input so that i had two computers audio output going into the same speaker
i believe this is what caused the problem as there was some type of ground loop happening as the signal went thru the Y splitter to another computer (note that it was totally OFF at the time) and then thru a crappy RCA cable (L/R/Video like a home theatre cheap cable) and then into a Delta 410 card breakout, into the 410 card installed in the OFF computer... and then i guess somehow the electrical signal travelled thru the motherboard + thru the psu of the other computer and then out its power connection, to a seperate powerbar strip ..
so there was an electrical loop and the noise was being caused literally by the power consumption of my computer.. freaky;)

the native instruments article i linked above suggests always plugging all the same related peripherals to the same powerbar strip + no other electrical or audio connections outside of that! i dont think it was the delta 410 cards fault.. but rather the loop that was created via the audio cable + power connections!! and the fact that they were plugged into seperate power strips

anyway, i can now turn my audio up full blast + i have ZERO interference again..
i was scared all that hard work transplanting this board into this new case had to be undone
or that i had to buy a new PSU!!! thank god that wasnt the cause.