Alright I just installed an Ht Omega Striker 7.1 in my computer and it's having this weird problem I just can't figure out.
My mother board is a Asus P5-ND I disabled the on-board audio via bios.
Okay so I installed the card, downloaded the latest drivers, every thing went smooth. I plugged my headset in (Roccat Kave) and messed around with a few settings to get the best audio, and disabled the stupid microphone echo.
Now here's where the weird problem starts, every thing was fine no hiss, great audio, until I open up any client (firefox, windows media player) then there is an incredibly loud hissing noise, and when I move my mouse it also makes a noise, when i scroll down the page, i hear a zip noise.
I double checked I plugged my headset in right, and I did, then I muted EVERY THING and still heard the sound (hissing on client opening, zipping hiss when scrolling down page)
I figured maybe wires were touching, so i made sure all my headset wires touched nothing and were far apart from the other wires, still I heard the sound.
I figured maybe this is because my headset is USB powered and plugged into my computer luckily I have a wall socket to usb adapter thing, so instead of plugging the USB into my computer i powered it through that, and I STILL HEAD THE SOUNDS.
Fine I say it must be the card, so I try it on an older pc I have, every thing is perfect...
I thought maybe it was my video card interfering with my soundcard somehow, but it can't be because my sound card is a good 2 or 3 PCI slots away
So basically I have no clue what else to do or how the hell to fix this and it's driving me crazy....
First thing I would check, when this happens, is to open the Control Panel -> sounds tab, and check if the green bar next to the soundcard is lighting up. If it is, then the soundcard is recieving an audio signal from the OS. If not [which I suspect], then you may be picking up some background EMI noise. You can try moving the card to another PCI slot and see if that helps.
At the place i work, i have a radio next to my computer, when ever i put the computer under any kind of load, i get loads of static and interference coming from the radio. after a ridiculously complex & in-comprehendable brainstorm, i relised if i move the radio somewere else it solve the problem.
Maybe that applys to your problem aswel, try what gamerk316 said as its the most reasonable explanation