Buzzing sound when I plug in my guitar

I first tried plugging my preamp out to my soundcard line in. This gave a buzzing sound.

So I tried to simplify and plugged my guitar to the mic in. Also a buzzing sound.

It's not interference picked up by the guitar because if I use it from the same place(in front of the computer) through the guitar amp there is no buzzing.

What could be wrong? My guitar is a Godin LGX and the sound card is a Fortissimo II.

You need a preamp. Best way to record guitar is to mic you amp, than plug mic into a preamp and than to computer.

Try turning off your computer monitor. It has degaussing coils in it that can cause havoc on guitar pickups. If turning your monitor off works, you can still work your computer if you've learned the keystrokes.